ORCID Profile
0000-0002-7981-508X
Current Organisations
University of Western Australia
,
University of New England
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Theoretical and Computational Chemistry not elsewhere classified | Free Radical Chemistry | Theoretical and Computational Chemistry | Quantum Chemistry | Organic Chemistry | Nanotechnology | Theory and Design of Materials | Electrochemistry | Nanoscale Characterisation | Molecular and Organic Electronics
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Biological Sciences | Energy Storage (excl. Hydrogen) |
Related Links
Publications
Blue phosphorene monolayers as potential nano sensors for volatile organic compounds under point defects
Publisher: Elsevier BV
Date: 08-2019
From Molecules with a Planar Tetracoordinate Carbon to an Astronomically Known C5H2 Carbene
Publisher: American Chemical Society (ACS)
Date: 15-04-2022
W4‐17: A diverse and high‐confidence dataset of atomization energies for benchmarking high‐level electronic structure methods
Publisher: Wiley
Date: 04-07-2017
DOI: 10.1002/JCC.24854
Abstract: Atomization reactions are among the most challenging tests for electronic structure methods. We use the first-principles Weizmann-4 (W4) computational thermochemistry protocol to generate the W4-17 dataset of 200 total atomization energies (TAEs) with 3σ confidence intervals of 1 kJ mol
Spontaneous shape and phase control of colloidal ZnSe nanocrystals by tailoring Se precursor reactivity
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CE00078J
Abstract: A novel synthetic method of shape and phase control of ZnSe nanocrystals by tailoring Se precursor reactivity is reported.
Investigation of an Unusual Crystal Habit of Hydrochlorothiazide Reveals Large Polar Enantiopure Domains and a Possible Crystal Nucleation Mechanism
Publisher: Wiley
Date: 24-06-2019
Abstract: The observation of an unusual crystal habit in the common diuretic drug hydrochlorothiazide (HCT), and identification of its subtle conformational chirality, has stimulated a detailed investigation of its crystalline forms. Enantiomeric conformers of HCT resolve into an unusual structure of conjoined enantiomorphic twin crystals comprising enantiopure domains of opposite chirality. The purity of the domains and the chiral molecular conformation are confirmed by spatially revolved synchrotron micro-XRD experiments and neutron diffraction, respectively. Macroscopic inversion twin symmetry observed between the crystal wings suggests a pseudoracemic structure that is not a solid solution or a layered crystal structure, but an unusual structural variant of conglomerates and racemic twins. Computed interaction energies for molecular pairs in the racemic and enantiopure polymorphs of HCT, and the observation of large opposing unit-cell dipole moments for the enantiopure domains in these twin crystals, suggest a plausible crystal nucleation mechanism for this unusual crystal habit.
Performance of DFT for C60 Isomerization Energies: A Noticeable Exception to Jacob’s Ladder
Publisher: American Chemical Society (ACS)
Date: 06-12-2019
Abstract: The ability to accurately calculate relative energies of fullerenes is important in many areas of computational nanotechnology. Because of the large size of fullerenes, their relative energies cannot normally be calculated by means of high-level ab initio procedures, and therefore, density functional theory (DFT) represents a cost-effective alternative. In an extensive benchmark study, we calculate the electronic energies of eight C
Thermoresponsive Graphene Membranes with Reversible Gating Regularity for Smart Fluid Control
Publisher: Wiley
Date: 04-02-2019
Efficient and selective sensing of nitrogen-containing gases by Si2BN nanosheets under pristine and pre-oxidized conditions
Publisher: Elsevier BV
Date: 03-2019
Evaluation of the Heats of Formation of Corannulene and C60 by Means of High-Level Theoretical Procedures
Publisher: American Chemical Society (ACS)
Date: 23-01-2013
DOI: 10.1021/JP312585R
Abstract: In this study, we address the issues associated with predicting usefully accurate heats of formation for moderately-sized molecules such as corannulene and C(60). We obtain a high-level theoretical heat of formation for corannulene through the use of reaction schemes that conserve increasingly larger molecular fragments between the reactants and products. The reaction enthalpies are obtained by means of the high-level, ab initio W1h thermochemical protocol, while accurate experimental enthalpies of formation for the other molecules involved in the reactions are obtained from the Active Thermochemical Tables (ATcT) network. Our best theoretical heat of formation for corannulene (Δ(f)H°(298)[C(20)H(10)(g)] = 485.2 ± 7.9 kJ mol(-1)) differs significantly from the currently accepted experimental value (Δ(f)H°(298)[C(20)H(10)(g)] = 458.5 ± 9.2 kJ mol(-1)), and this suggests that re-examination of the experimental data may be in order. We have used our theoretical heat of formation for corannulene to obtain a predicted heat of formation of C(60) through reactions that involve only corannulene and planar polyacenes. Current experimental values span a range of ~200 kJ mol(-1). Our reaction enthalpies are obtained by means of double-hybrid density functional theory in conjunction with a large quadruple-ζ basis set, while accurate experimental heats of formation (or our theoretical value in the case of corannulene) are used for the other molecules involved. Our best theoretical heat of formation for C(60) (Δ(f)H°(298)[C(60)(g)] = 2521.6 kJ mol(-1)) suggests that the experimental value adopted by the NIST thermochemical database (Δ(f)H°(298)[C(60)(g)] = 2560 ± 100 kJ mol(-1)) should be revised downward.
Comment on “Revised electron affinity of SF6 from kinetic data” [J. Chem. Phys. 136, 121102 (2012)]
Publisher: AIP Publishing
Date: 21-05-2012
DOI: 10.1063/1.4719180
Abstract: The adiabatic electron affinity (AEA) of SF6 has been calculated near the relativistic CCSDT(Q) basis set limit. Our best theoretical value (1.0340 ± 0.03 eV) is in excellent agreement with the recently revised experimental value of 1.03 ± 0.05 eV reported by Troe et al. [J. Chem. Phys. 136, 121102 (2012)]10.1063/1.3698170. While our best nonrelativistic, cl ed-nuclei, valence CCSD(T) basis set limit value of 0.9058 eV is in good accord with the previously reported CCSD(T)/CBS values, to obtain an accurate AEA, several additional contributions need to be taken into account. The most important one is scalar-relativistic effects (0.0839 eV), followed by inner-shell correlation (0.0216 eV) and post-CCSD(T) correlation effects (0.0248 eV), the latter almost entirely due to connected quadruple excitations. The diagonal Born-Oppenheimer correction is an order of magnitude less important at −0.0022 eV.
W4 theory for computational thermochemistry: In pursuit of confident sub-kJ/mol predictions
Publisher: AIP Publishing
Date: 12-10-2006
DOI: 10.1063/1.2348881
Abstract: In an attempt to improve on our earlier W3 theory [A. D. Boese et al., J. Chem. Phys. 120, 4129 (2004)] we consider such refinements as more accurate estimates for the contribution of connected quadruple excitations (T̂4), inclusion of connected quintuple excitations (T̂5), diagonal Born-Oppenheimer corrections (DBOC), and improved basis set extrapolation procedures. Revised experimental data for validation purposes were obtained from the latest version of the Active Thermochemical Tables thermochemical network. The recent CCSDT(Q) method offers a cost-effective way of estimating T̂4, but is insufficient by itself if the molecule exhibits some nondynamical correlation. The latter considerably slows down basis set convergence for T̂4, and anomalous basis set convergence in highly polar systems makes two-point extrapolation procedures unusable. However, we found that the CCSDTQ−CCSDT(Q) difference converges quite rapidly with the basis set, and that the formula 1.10[CCSDT(Q)∕cc-pVTZ+CCSDTQ∕cc-pVDZ-CCSDT(Q)∕cc-pVDZ] offers a very reliable as well as fairly cost-effective estimate of the basis set limit T̂4 contribution. The T̂5 contribution converges very rapidly with the basis set, and even a simple double-zeta basis set appears to be adequate. The largest T̂5 contribution found in the present work is on the order of 0.5kcal∕mol (for ozone). DBOCs are significant at the 0.1kcal∕mol level in hydride systems. Post-CCSD(T) contributions to the core-valence correlation energy are only significant at that level in systems with severe nondynamical correlation effects. Based on the accumulated experience, a new computational thermochemistry protocol for first- and second-row main-group systems, to be known as W4 theory, is proposed. Its computational cost is not insurmountably higher than that of the earlier W3 theory, while performance is markedly superior. Our W4 atomization energies for a number of key species are in excellent agreement (better than 0.1kcal∕mol on average, 95% confidence intervals narrower than 1kJ∕mol) with the latest experimental data obtained from Active Thermochemical Tables. Lower-cost variants are proposed: the sequence W1→W2.2→W3.2→W4lite→W4 is proposed as a converging hierarchy of computational thermochemistry methods. A simple a priori estimate for the importance of post-CCSD(T) correlation contributions (and hence a pessimistic estimate for the error in a W2-type calculation) is proposed.
The CH3CHOO 'Criegee intermediate' and its anion: Isomers, infrared spectra, and W3-F12 energetics
Publisher: Elsevier BV
Date: 02-2015
π–π interactions between benzene and graphene by means of large-scale DFT-D4 calculations
Publisher: Elsevier BV
Date: 09-2022
Sensing of volatile organic compounds on two-dimensional nitrogenated holey graphene, graphdiyne, and their heterostructure
Publisher: Elsevier BV
Date: 08-2020
W4 thermochemistry of P2and P4. Is the CODATA heat of formation of the phosphorus atom correct?
Publisher: Informa UK Limited
Date: 10-10-2007
W4-11: A high-confidence benchmark dataset for computational thermochemistry derived from first-principles W4 data
Publisher: Elsevier BV
Date: 07-2011
G4(MP2)-XK: A Variant of the G4(MP2)-6X Composite Method with Expanded Applicability for Main-Group Elements up to Radon
Publisher: American Chemical Society (ACS)
Date: 09-07-2019
Abstract: In the present study, we have devised the G4(MP2)-XK composite method that covers species with up to fifth-row main-group elements (i.e., up to Rn). This new protocol is based on the previously published G4(MP2)-6X method, which has a general accuracy of ∼5 kJ mol
A computational investigation of the sulphuric acid‐catalysed 1,4‐hydrogen transfer in higher Criegee intermediates
Publisher: Wiley
Date: 07-02-2018
DOI: 10.1002/QUA.25599
To bridge or not to bridge: The role of sulfuric acid in the Beckmann rearrangement
Publisher: Elsevier BV
Date: 08-2016
Graphitic carbon nitride nano sheets functionalized with selected transition metal dopants
Publisher: IOP Publishing
Date: 06-08-2018
Abstract: Proficient capture of carbon dioxide (CO
Desymmetrization and Kinetic Resolution of Endoperoxides Using a Bifunctional Organocatalyst
Publisher: American Chemical Society (ACS)
Date: 08-08-2023
Perylene Bisimide Cyclophanes as Biaryl Enantiomerization Catalysts─Explorations into π–π Catalysis and Host–Guest Chirality Transfer
Publisher: American Chemical Society (ACS)
Date: 21-01-2022
Abstract: The racemization of axially chiral biaryls is a fundamental step toward transforming kinetic resolutions into dynamic kinetic resolutions (DKRs). The high enantiomerization barriers of many biaryl compounds of synthetic relevance, however, may render DKR strategies challenging. Here, we computationally explore the potential of a
Reactive Compression Molding Post-Inverse Vulcanization: A Method to Assemble, Recycle, and Repurpose Sulfur Polymers and Composites
Publisher: Wiley
Date: 18-06-2020
Parental Relations and Family Functioning in Non-Offending Caregivers of Abused Children
Publisher: Springer Science and Business Media LLC
Date: 05-12-2017
S66x8 noncovalent interactions revisited: new benchmark and performance of composite localized coupled-cluster methods
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP03938A
Abstract: The S66x8 noncovalent interactions benchmark has been re-evaluated at the “sterling silver” level. Against this, a selection of computationally more economical alternatives has been assayed, ranging from localized CC to double hybrids and SAPT(DFT).
Observation of defect density dependent elastic modulus of graphene
Publisher: AIP Publishing
Date: 31-07-2023
DOI: 10.1063/5.0157104
Abstract: The recent decade has witnessed a tremendous development of graphene applications in many fields however, as one of the key considerations, the mechanical properties of graphene still remain largely unexplored. Herein, by employing focused ion beam irradiation, graphene with various defect levels is obtained and further investigated by using Raman spectroscopy and scanning tunneling microscopy. Specially, our atomic force microscopy based nanomechanical property measurement demonstrates a clear defect density dependent behavior in the elastic modulus of graphene on a substrate as the defect density is higher than a threshold value of 1012 cm−2, where a clear decay is observed in the stiffness of graphene. This defect density dependence is mainly attributed to the appearance of amorphous graphene, which is further confirmed with our molecular dynamics calculations. Therefore, our reported result provides an essential guidance to enable the rational design of graphene materials in nanodevices, especially from the perspective of mechanical properties.
Basis set convergence of post-CCSD contributions to molecular atomization energies
Publisher: AIP Publishing
Date: 10-08-2007
DOI: 10.1063/1.2755751
Abstract: Basis set convergence of correlation effects on molecular atomization energies beyond the coupled cluster with singles and doubles (CCSD) approximation has been studied near the one-particle basis set limit. Quasiperturbative connected triple excitations, (T), converge more rapidly than L−3 (where L is the highest angular momentum represented in the basis set), while higher-order connected triples, T3−(T), converge more slowly—empirically, ∝L−5∕2. Quasiperturbative connected quadruple excitations, (Q), converge smoothly as ∝L−3 starting with the cc-pVTZ basis set, while the cc-pVDZ basis set causes overshooting of the contribution in highly polar systems. Higher-order connected quadruples display only weak, but somewhat erratic, basis set dependence. Connected quintuple excitations converge very rapidly with the basis set, to the point where even an unpolarized double-zeta basis set yields useful numbers. In cases where fully iterative coupled cluster up to connected quintuples (CCSDTQ5) calculations are not an option, CCSDTQ(5) (i.e., coupled cluster up to connected quadruples plus a quasiperturbative connected quintuples correction) cannot be relied upon in the presence of significant nondynamical correlation, whereas CCSDTQ(5)Λ represents a viable alternative. Connected quadruples corrections to the core-valence contribution are thermochemically significant in some systems. We propose an additional variant of W4 theory [A. Karton et al., J. Chem. Phys. 125, 144108 (2006)], denoted W4.4 theory, which is shown to yield a rms deviation from experimental atomization energies (active thermochemical tables, ATcT) of only 0.05kcal∕mol for systems for which ATcT values are available. We conclude that “3σ⩽1kJ∕mol” thermochemistry is feasible with current technology, but that the more ambitious goal of ±10cm−1 accuracy is illusory, at least for atomization energies.
Sensitivity enhancement of stanene towards toxic SO2 and H2S
Publisher: Elsevier BV
Date: 11-2019
Mechanistic insights into the water-catalysed ring-opening reaction of vitamin E by means of double-hybrid density functional theory
Publisher: Elsevier BV
Date: 09-2018
Quantum chemical electron impact mass spectrum prediction for de novo structure elucidation: Assessment against experimental reference data and comparison to competitive fragmentation modeling
Publisher: Wiley
Date: 26-08-2017
DOI: 10.1002/QUA.25460
The S66 Non-Covalent Interactions Benchmark Reconsidered Using Explicitly Correlated Methods Near the Basis Set Limit
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CH17588
Abstract: The S66 benchmark for non-covalent interactions has been re-evaluated using explicitly correlated methods with basis sets near the one-particle basis set limit. It is found that post-MP2 ‘high-level corrections’ are treated adequately well using a combination of CCSD(F12*) with (aug-)cc-pVTZ-F12 basis sets on the one hand, and (T) extrapolated from conventional CCSD(T)/heavy-aug-cc-pV{D,T}Z on the other hand. Implications for earlier benchmarks on the larger S66×8 problem set in particular, and for accurate calculations on non-covalent interactions in general, are discussed. At a slight cost in accuracy, (T) can be considerably accelerated by using sano-V{D,T}Z+ basis sets, whereas half-counterpoise CCSD(F12*)(T)/cc-pVDZ-F12 offers the best compromise between accuracy and computational cost.
A high-level quantum chemical study of the thermodynamics associated with chlorine transfer between N-chlorinated nucleobases
Publisher: IOP Publishing
Date: 12-05-2023
Abstract: The relative free energies of the isomers formed upon N -chlorination of each nitrogen atom within the DNA nucleobases (adenine, guanine, and thymine) have been obtained using the high-level G4(MP2) composite ab initio method (the free energies of the N -chlorinated isomers of cytosine have been reported at the same level of theory previously). Having identified the lowest energy N -chlorinated derivatives for each nucleobase, we have computed the free energies associated with chlorine transfer from N -chlorinated nucleobases to other unsubstituted bases. Our results provide quantitative support pertaining to the results of previous experimental studies, which demonstrated that rapid chlorine transfer occurs from N -chlorothymidine to cytidine or adenosine. The results of our calculations in the gas-phase reveal that chlorine transfer from N -chlorothymine to either cytosine, adenine, or guanine proceed via exergonic processes with Δ G o values of −50.3 (cytosine), −28.0 (guanine), and −6.7 (adenine) kJ mol –1 . Additionally, we consider the effect of aqueous solvation by augmenting our gas-phase G4(MP2) energies with solvation corrections obtained using the conductor-like polarizable continuum model. In aqueous solution, we obtain the following G4(MP2) free energies associated with chlorine transfer from N -chlorothymine to the three other nucleobases: −58.4 (cytosine), −26.4 (adenine), and −18.7 (guanine) kJ mol –1 . Therefore, our calculations, whether in the gas phase or in aqueous solution, clearly indicate that chlorine transfer from any of the N -chlorinated nucleobases to cytosine provides a thermodynamic sink for the active chlorine. This thermodynamic preference for chlorine transfer to cytidine may be particularly deleterious since previous experimental studies have shown that nitrogen-centered radical formation (via N–Cl bond homolysis) is more easily achieved in N -chlorinated cytidine than in other N -chlorinated nucleosides.
Manganese-Catalyzed Hydroboration of Terminal Olefins and Metal-Dependent Selectivity in Internal Olefin Isomerization–Hydroboration
Publisher: American Chemical Society (ACS)
Date: 16-12-2020
Benchmark Thermochemistry of the CnH2n+2 Alkane Isomers (n = 2−8) and Performance of DFT and Composite Ab Initio Methods for Dispersion-Driven Isomeric Equil
Publisher: American Chemical Society (ACS)
Date: 07-2009
DOI: 10.1021/JP904369H
Abstract: The thermochemistry of linear and branched alkanes with up to eight carbons has been reexamined by means of W4, W3.2lite and W1h theories. "Quasi-W4" atomization energies have been obtained via isodesmic and hypohomodesmotic reactions. Our best atomization energies at 0 K (in kcal/mol) are 1220.04 for n-butane, 1497.01 for n-pentane, 1774.15 for n-hexane, 2051.17 for n-heptane, 2328.30 for n-octane, 1221.73 for isobutane, 1498.27 for isopentane, 1501.01 for neopentane, 1775.22 for isohexane, 1774.61 for 3-methylpentane, 1775.67 for diisopropyl, 1777.27 for neohexane, 2052.43 for isoheptane, 2054.41 for neoheptane, 2330.67 for isooctane, and 2330.81 for hexamethylethane. Our best estimates for DeltaH(f,298K)(o) are -30.00 for n-butane, -34.84 for n-pentane, -39.84 for n-hexane, -44.74 for n-heptane, -49.71 for n-octane, -32.01 for isobutane, -36.49 for isopentane, -39.69 for neopentane, -41.42 for isohexane, -40.72 for 3-methylpentane, -42.08 for diisopropyl, -43.77 for neohexane, -46.43 for isoheptane, -48.84 for neoheptane, -53.29 for isooctane, and -53.68 for hexamethylethane. These are in excellent agreement (typically better than 1 kJ/mol) with the experimental heats of formation at 298 K obtained from the CCCBDB and/or NIST Chemistry WebBook databases. However, at 0 K, a large discrepancy between theory and experiment (1.1 kcal/mol) is observed for only neopentane. This deviation is mainly due to the erroneous heat content function for neopentane used in calculating the 0 K CCCBDB value. The thermochemistry of these systems, especially that of the larger alkanes, is an extremely difficult test for density functional methods. A posteriori corrections for dispersion are essential. Particularly for the atomization energies, the B2GP-PLYP and B2K-PLYP double hybrids and the PW6B95 hybrid meta-GGA clearly outperform other DFT functionals.
Heats of Formation for CrO, CrO2, and CrO3: An Extreme Challenge for Black-Box Composite Procedures
Publisher: American Chemical Society (ACS)
Date: 21-08-2012
DOI: 10.1021/CT300495M
Abstract: In the present study, we use composite methods, denoted CM(5)Λ and CM5, with post-CCSD(T) terms up to CCSDTQ(5)Λ and CCSDTQ5, respectively, to evaluate the atomization energies for CrO, CrO2, and CrO3. The heats of formation (ΔHf,298) based on our best estimated atomization energies are 198.3 ± 5 kJ mol(-1) (CrO), -81.3 ± 5 kJ mol(-1) (CrO2), and -286.8 ± 20 kJ mol(-1) (CrO3). Standard G4-type composite methods yield atomization energies that are adequate for CrO, less good for CrO2, and least good for CrO3. CrO3 is highly multireference in character, and therefore, a "black box" approach of using a single-reference RHF wave function is inadequate, even for "high-level" G4-type methods. We find that, for CrO3, there is a very large difference in the G4 atomization energies depending on whether an RHF or a UHF reference is used, which is mainly associated with large differences in the MP4 components. In general, we propose that a large R-versus-U difference is likely to be an indication of potential problems in the theoretical treatment. Going beyond G4 to a more rigorous UCCSD(T)-based composite scheme [termed U-CM(3:[DZ,TZ]) in the present study], we again find a large difference (but significantly smaller than that for G4) between the CrO3 atomization energies based on RHF or UHF references. Intriguingly, the use of Brueckner orbitals as reference orbitals in all components, as in the corresponding Brueckner Doubles (BD) procedure [B-CM(3:[DZ,TZ])], produces results for CrO3 that are independent of whether RHF or UHF orbitals are used as the starting point.
π‐π Catalysis Made Asymmetric—Enantiomerization Catalysis Mediated by the Chiral π‐System of a Perylene Bisimide Cyclophane
Publisher: Wiley
Date: 04-04-2023
Abstract: Enzymes actuate catalysis through a combination of transition state stabilization and ground state destabilization, inducing enantioselectivity through chiral binding sites. Here, we present a supramolecular model system which employs these basic principles to catalyze the enantiomerization of [5]helicene. Catalysis is hereby mediated not through a network of functional groups but through π‐π catalysis exerted from the curved aromatic framework of a chiral perylene bisimide (PBI) cyclophane offering a binding pocket that is intricately complementary with the enantiomerization transition structure. Although transition state stabilization originates simply from dispersion and electrostatic interactions, enantiomerization kinetics are accelerated by a factor of ca. 700 at 295 K. Comparison with the meso‐congener of the catalytically active cyclophane shows that upon configurational inversion in only one PBI moiety the catalytic effect is lost, highlighting the importance of precise transition structure recognition in supramolecular enzyme mimics.
CCSDT(Q)/CBS thermochemistry for the D5h → D10h isomerization in the C10 carbon cluster: Getting the right answer for the right reason
Publisher: Elsevier BV
Date: 08-2018
Explicitly correlated Wn theory: W1-F12 and W2-F12
Publisher: AIP Publishing
Date: 28-03-2012
DOI: 10.1063/1.3697678
Abstract: In an attempt to extend the applicability of the W1 and W2 ab initio computational thermochemistry methods, we propose explicitly correlated versions thereof, denoted W1-F12 and W2-F12. In W2-F12, we can “save” one cardinal number (viz., angular momentum) in the basis set sequences without loss in accuracy in W1-F12, we can do so for first-row compounds but not for second-row compounds. At a root mean square deviation (RMSD) = 0.19 kcal/mol for the first-row molecules in the W4-11 benchmark dataset, W1-F12 is in fact superior to ordinary W1 theory. For the entire W4-11 set, W2-F12 yields a RMSD = 0.20 kcal/mol, comparable to 0.19 kcal/mol from ordinary W2 theory. The extended applicability ranges of W1-F12 and W2-F12 are not just due to the lower computational cost but also to greatly reduced memory and especially storage requirements. They are illustrated through applications to nucleic acids and to polyacenes (with up to four rings), for which the following revised gas-phase heats of formation are found: \\documentclass[12pt]{minimal}\\begin{document}$\\Delta _fH^\\circ _{298}$\\end{document}ΔfH298∘ = 19.6 (benzene), 34.94 (naphthalene), 53.9, (anthracene), 73.9 (naphthacene/tetracene), 54.9 (adenine), −16.3 (cytosine), 5.1 (guanine), −80.6 (thymine), and −71.6 (uracil) kcal/mol. Our theoretical values for the DNA/RNA bases largely confirm recent predictions based on much lower-level calculations. The W1-F12 theoretical values for benzene, naphthalene, and anthracene are in very good to reasonable agreement with experiment. However, both W1-F12 and other computational estimates show that the accepted experimental value for naphthacene cannot be reconciled with those for the lower acenes: we suggest that \\documentclass[12pt]{minimal}\\begin{document}$\\Delta _f H^\\circ _{298}$\\end{document}ΔfH298∘[naphthacene(g)] = 74.25 ± 1 kcal/mol is a more realistic estimate.
Metal functionalized inorganic nano-sheets as promising materials for clean energy storage
Publisher: Elsevier BV
Date: 03-2019
Performance of W4 theory for spectroscopic constants and electrical properties of small molecules
Publisher: AIP Publishing
Date: 11-10-2010
DOI: 10.1063/1.3489113
Abstract: Accurate spectroscopic constants and electrical properties of small molecules are determined by means of W4 and post-W4 theories. For a set of 28 first- and second-row diatomic molecules for which very accurate experimental spectroscopic constants are available, W4 theory affords near-spectroscopic or better predictions. Specifically, the root-mean-square deviations (RMSDs) from experiment are 0.04 pm for the equilibrium bond distances (re), 1.03 cm−1 for the harmonic frequencies (ωe), 0.20 cm−1 for the first anharmonicity constants (ωexe), 0.10 cm−1 for the second anharmonicity constants (ωeye), and 0.001 cm−1 for the vibration-rotation coupling constants (αe). These RMSDs imply 95% confidence intervals of about 0.1 pm for re, 2.0 cm−1 for ωe, 0.4 cm−1 for ωexe, and 0.2 cm−1 for ωeye. We find that post-CCSD(T) contributions are essential to achieve such narrow confidence intervals for re and ωe, but have little effect on ωexe and αe, and virtually none on ωeye. Higher-order connected triples T̂3−(T) improve the agreement with experiment for the hydride systems, but their inclusion (in the absence of T̂4) tends to worsen the agreement with experiment for the nonhydride systems. Connected quadruple excitations T̂4 have significant and systematic effects on re, ωe, and ωexe, in particular they universally increase re (by up to 0.5 pm), universally reduce ωe (by up to 32 cm−1), and universally increase ωexe (by up to 1 cm−1). Connected quintuple excitations T̂5 are spectroscopically significant for ωe of the nonhydride systems, affecting ωe by up to 4 cm−1. Diagonal Born–Oppenheimer corrections have systematic and spectroscopically significant effects on re and ωe of the hydride systems, universally increasing re by 0.01–0.06 pm and decreasing ωe by 0.3–2.1 cm−1. Obtaining re and ωe of the pathologically multireference BN and BeO systems with near-spectroscopic accuracy requires large basis sets in the core-valence CCSD(T) step and augmented basis sets in the valence post-CCSD(T) steps in W4 theory. The triatomic molecules H2O, CO2, and O3 are also considered. The equilibrium geometries and harmonic frequencies (with the exception of the asymmetric stretch of O3) are obtained with near-spectroscopic accuracy at the W4 level. The asymmetric stretch of ozone represents a severe challenge to W4 theory, in particular the connected quadruple contribution converges very slowly with the basis set size. Finally, the importance of post-CCSD(T) correlation effects for electrical properties, namely, dipole moments (μ), polarizabilities (α), and first hyperpolarizabilities (β), is evaluated.
Can DFT and ab initio methods adequately describe binding energies in strongly interacting C6X6⋯C2X π–π complexes?
Publisher: Elsevier BV
Date: 08-2017
Analysis of Clinical Phenotypes through Machine Learning of First-Line H. pylori Treatment in Europe during the Period 2013–2022: Data from the European Registry on H. pylori Management (Hp-EuReg)
Publisher: MDPI AG
Date: 10-09-2023
Benchmark ab Initio Conformational Energies for the Proteinogenic Amino Acids through Explicitly Correlated Methods. Assessment of Density Functional Methods
Publisher: American Chemical Society (ACS)
Date: 22-12-2015
Abstract: The relative energies of the YMPJ conformer database of the 20 proteinogenic amino acids, with N- and C-termination, have been re-evaluated using explicitly correlated coupled cluster methods. Lower-cost ab initio methods such as MP2-F12 and CCSD-F12b actually are outperformed by double-hybrid DFT functionals in particular, the DSD-PBEP86-NL double hybrid performs well enough to serve as a secondary standard. Among range-separated hybrids, ωB97X-V performs well, while B3LYP-D3BJ does surprisingly well among traditional DFT functionals. Treatment of dispersion is important for the DFT functionals for the YMPJ set, D3BJ generally works as well as the NL nonlocal dispersion functional. Basis set sensitivity for DFT calculations on these conformers is weak enough that def2-TZVP is generally adequate. For conformer corrections to heats of formation, B3LYP-D3BJ and especially DSD-PBEP86-D3BJ or DSD-PBEP86-NL are adequate for all but the most exacting applications. The revised geometries and energetics for the YMPJ database have been made available as Supporting Information and should be useful in the parametrization and validation of molecular mechanics force fields and other low-cost methods. The very recent dRPA75 method yields good performance, without resorting to an empirical dispersion correction, but is still outperformed by DSD-PBEP86-D3BJ and particularly DSD-PBEP86-NL. Core-valence corrections are comparable in importance to improvements beyond CCSD(T*)/cc-pVDZ-F12 in the valence treatment.
Tribute to Leo Radom
Publisher: American Chemical Society (ACS)
Date: 05-12-2019
π‐π Catalysis Made Asymmetric—Enantiomerization Catalysis Mediated by the Chiral π‐System of a Perylene Bisimide Cyclophane
Publisher: Wiley
Date: 04-04-2023
Abstract: Enzymes actuate catalysis through a combination of transition state stabilization and ground state destabilization, inducing enantioselectivity through chiral binding sites. Here, we present a supramolecular model system which employs these basic principles to catalyze the enantiomerization of [5]helicene. Catalysis is hereby mediated not through a network of functional groups but through π‐π catalysis exerted from the curved aromatic framework of a chiral perylene bisimide (PBI) cyclophane offering a binding pocket that is intricately complementary with the enantiomerization transition structure. Although transition state stabilization originates simply from dispersion and electrostatic interactions, enantiomerization kinetics are accelerated by a factor of ca. 700 at 295 K. Comparison with the meso‐congener of the catalytically active cyclophane shows that upon configurational inversion in only one PBI moiety the catalytic effect is lost, highlighting the importance of precise transition structure recognition in supramolecular enzyme mimics.
Functionalized Two-Dimensional Nanoporous Graphene as Efficient Global Anode Materials for Li-, Na-, K-, Mg-, and Ca-Ion Batteries
Publisher: American Chemical Society (ACS)
Date: 08-04-2020
Moiré patterns arising from bilayer graphone/graphene superlattice
Publisher: Springer Science and Business Media LLC
Date: 04-2020
DOI: 10.1007/S12274-020-2744-6
Abstract: Moiré patterns from two-dimensional (2D) graphene heterostructures assembled via van der Waals interactions have sparked considerable interests in physics with the purpose to tailor the electronic properties of graphene. Here we report for the first time the observation of moiré patterns arising from a bilayer graphone/graphene superlattice produced through direct single-sided hydrogenation of a bilayer graphene on substrate. Compared to pristine graphene, the bilayer superlattice exhibits a rippled surface and two types of moiré patterns are observed: triangular and linear moiré patterns with the periodicities of 11 nm and 8–9 nm, respectively. These moiré patterns are revealed from atomic force microscopy and further confirmed by following fast Fourier transform (FFT) analysis. Density functional theory (DFT) calculations are also performed and the optimized lattice constants of bilayer superlattice heterostructure are in line with our experimental analysis. These findings show that well-defined triangular and linear periodic potentials can be introduced into the graphene system through the single-sided hydrogenation and also open a route towards the tailoring of electronic properties of graphene by various moiré potentials.
Can density functional theory ‘Cope’ with highly fluxional shapeshifting molecules?
Publisher: Elsevier BV
Date: 2021
Determination of Barrier Heights for Proton Exchange in Small Water, Ammonia, and Hydrogen Fluoride Clusters with G4(MP2)-Type, MPn, and SCS-MPn Procedures—A Caveat
Publisher: American Chemical Society (ACS)
Date: 08-08-2012
DOI: 10.1021/CT3004723
Abstract: Calculation of accurate water-water interaction energies is of fundamental importance in computational modeling of many biological and chemical phenomena. We have obtained benchmark barrier heights for proton-exchange reactions and complexation energies in water clusters (H2O)n (n = 1-6) by means of the high-level W1-F12 procedure. We find that lower-cost composite procedures (e.g., G4(MP2) and G4(MP2)-6X), as well as MP2 and SCS-MP2, exhibit surprisingly poor performance for the barrier heights of reactions involving multiple proton exchanges. Moreover, the performance significantly deteriorates with increasing size of the clusters. Similar observations apply to complexation energies in water clusters, and to barrier heights for proton exchange in ammonia and hydrogen fluoride clusters. We propose a modified version of G4(MP2)-6X (denoted G4(MP2)-6X+) that includes sp- and d-diffuse functions in the CCSD(T) term, which gives excellent proton-exchange barrier heights at a computational cost only slightly greater than that of standard G4(MP2). G4(MP2)-6X+ also leads to a substantial improvement over G4(MP2) and G4(MP2)-6X for the calculation of electron affinities.
An assessment of theoretical procedures forπ-conjugation stabilisation energies in enones
Publisher: Informa UK Limited
Date: 02-12-2014
Thermochemistry of icosahedral closo-dicarboranes
Publisher: Canadian Science Publishing
Date: 12-2016
Abstract: We obtained accurate thermochemical properties for the ortho-, meta-, and para-dicarborane isomers (C 2 B 10 H 12 ) by means of explicitly correlated high-level thermochemical procedures. The thermochemical properties include heats of formation, isomerization energies, C–H and B–H bond dissociation energies (BDEs), and ionization potentials. Of these only the ionization potentials are known experimentally. Our best theoretical ionization potentials, obtained by means of the ab initio W1–F12 thermochemical protocol, was 241.50 kcal mol –1 (para-dicarborane), 238.45 kcal mol –1 (meta-dicarborane), and 236.54 kcal mol –1 (ortho-dicarborane). These values agree with the experimental values adopted by the National Institute of Standards and Technology (NIST) thermochemical tables to within overlapping uncertainties. However, they suggest that the experimental values may represent significant underestimations. For all isomers, the C–H BDEs are systematically higher than the B–H BDEs because of the relative stability of the boron-centred radicals. The C–H BDEs for the three isomers cluster within a narrow energetic interval, namely between 110.8 kcal mol –1 (para-dicarborane) and 111.7 kcal mol –1 (meta-dicarborane). The B–H BDEs cluster within a larger interval ranging between 105.8 and 108.1 kcal mol –1 (both obtained for ortho-dicarborane). We used our benchmark W1–F12 data to assess the performance of a number of lower cost composite ab initio methods. We found that the Gaussian-3 procedures (G3(MP2)B3 and G3B3) result in excellent performance with overall root-mean-square deviations (RMSDs) of 0.3–0.4 kcal mol –1 for the isomerization, ionization, and bond dissociation energies. However, the Gaussian-4 procedures (G4, G4(MP2), and G4(MP2)-6X) showed relatively poor performance with overall RMSDs of 1.3–3.7 kcal mol –1 .
Heats of formation of the amino acids re-examined by means of W1-F12 and W2-F12 theories
Publisher: Springer Science and Business Media LLC
Date: 16-04-2014
Assessment of Theoretical Procedures for Calculating Barrier Heights for a Diverse Set of Water-Catalyzed Proton-Transfer Reactions
Publisher: American Chemical Society (ACS)
Date: 12-04-2012
DOI: 10.1021/JP301499Y
Abstract: Accurate electronic barrier heights are obtained for a set of nine proton-transfer tautomerization reactions, which are either (i) uncatalyzed, (ii) catalyzed by one water molecule, or (iii) catalyzed by two water molecules. The barrier heights for reactions (i) and (ii) are obtained by means of the high-level ab initio W2.2 thermochemical protocol, while those for reaction (iii) are obtained using the W1 protocol. These three sets of benchmark barrier heights allow an assessment of the performance of more approximate theoretical procedures for the calculation of barrier heights of uncatalyzed and water-catalyzed reactions. We evaluate initially the performance of the composite G4 procedure and variants thereof (e.g., G4(MP2) and G4(MP2)-6X), as well as that of standard ab initio procedures (e.g., MP2, SCS-MP2, and MP4). We find that the performance of the G4(MP2)-type thermochemical procedures deteriorates with the number of water molecules involved in the catalysis. This behavior is linked to deficiencies in the MP2-based basis-set-correction term in the G4(MP2)-type procedures. This is remedied in the MP4-based G4 procedure, which shows good performance for both the uncatalyzed and the water-catalyzed reactions, with mean absolute deviations (MADs) from the benchmark values lying below the threshold of "chemical accuracy" (arbitrarily defined as 1 kcal mol(-1) ≈ 4.2 kJ mol(-1)). We also examine the performance of a large number of density functional theory (DFT) and double-hybrid DFT (DHDFT) procedures. We find that, with few exceptions (most notably PW6-B95 and B97-2), the performance of the DFT procedures that give good results for the uncatalyzed reactions deteriorates with the number of water molecules involved in the catalysis. The DHDFT procedures, on the other hand, show excellent performance for both the uncatalyzed and catalyzed reactions. Specifically, almost all of them afford MADs below the "chemical accuracy" threshold, with ROB2-PLYP and B2K-PLYP showing the best overall performance.
Comment on: “Estimating the Hartree–Fock limit from finite basis set calculations” [Jensen F (2005) Theor Chem Acc 113:267]
Publisher: Springer Science and Business Media LLC
Date: 06-12-2005
Stability of the chlorinated derivatives of the DNA/RNA nucleobases, purine and pyrimidine toward radical formation via homolytic CCl bond dissociation
Publisher: Wiley
Date: 18-11-2016
DOI: 10.1002/QUA.25319
Basis set convergence of explicitly correlated double-hybrid density functional theory calculations
Publisher: AIP Publishing
Date: 13-10-2011
DOI: 10.1063/1.3647980
Abstract: The basis set convergence of explicitly correlated double-hybrid density functional theory (DFT) is investigated using the B2GP-PLYP functional. As reference values, we use basis set limit B2GP-PLYP-F12 reaction energies extrapolated from the aug′-cc-pV(Q+d)Z and aug′-cc-pV(5+d)Z basis sets. Explicitly correlated double-hybrid DFT calculations converge significantly faster to the basis set limit than conventional calculations done with basis sets saturated up to the same angular momentum (typically, one “gains” one angular momentum in the explicitly correlated calculations). In explicitly correlated F12 calculations the VnZ-F12 basis sets converge faster than the orbital A′VnZ basis sets. Furthermore, basis set convergence of the MP2-F12 component is apparently faster than that of the underlying Kohn-Sham calculation. Therefore, the most cost-effective approach consists of combining the MP2-F12 correlation energy from a comparatively small basis set such as VDZ-F12 with a DFT energy from a larger basis set such as aug′-cc-pV(T+d)Z.
Heats of Formation of Beryllium, Boron, Aluminum, and Silicon Re-examined by Means of W4 Theory
Publisher: American Chemical Society (ACS)
Date: 14-06-2007
DOI: 10.1021/JP071690X
Abstract: Benchmark total atomization energies (TAE0 values) were obtained, by means of our recent W4 theory [Karton, A. Rabinowitz, E. Martin, J. M. L. Ruscic, B. J. Chem. Phys. 2006, 125, 144108], for the molecules Be2, BeF2, BeCl2, BH, BF, BH3, BHF2, B2H6, BF3, AlF, AlF3, AlCl3, SiH4, Si2H6, and SiF4. We were then able to deduce "semi-experimental" heats of formation for the elements beryllium, boron, aluminum, and silicon by combining the calculated TAE0 values with experimental heats of formation obtained from reactions that do not involve the species Be(g), B(g), Al(g), and Si(g). The elemental heats of formation are fundamental thermochemical quantities that are required whenever a molecular heat of formation has to be derived from a calculated binding energy. Our recommended DeltaH degrees f,0 [A(g)] values are Be 76.4+/-0.6 kcal/mol, B 135.1+/-0.2 kcal/mol, Al 80.2+/-0.4 kcal/mol, and Si 107.2+/-0.2 kcal/mol. (The corresponding values at 298.15 K are 77.4, 136.3, 80.8, and 108.2 kcal/mol, respectively.) The Be value is identical to the CODATA recommendation (but with half of the uncertainty), while the B, Al, and Si values represent substantial revisions from established earlier reference data. The revised B and Si values are in agreement with earlier semi-ab initio derivations but carry much smaller uncertainties.
Chemically induced repair, adhesion, and recycling of polymers made by inverse vulcanization
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC00855A
Abstract: Polymers made by inverse vulcanization can be assembled, repaired, and recycled at room temperature through nucleophile-catalyzed S–S metathesis.
Assessment of theoretical procedures for a diverse set of isomerization reactions involving double-bond migration in conjugated dienes
Publisher: Elsevier BV
Date: 09-2014
Highly Accurate First-Principles Benchmark Data Sets for the Parametrization and Validation of Density Functional and Other Approximate Methods. Derivation of a Robust, Generally Applicable, Double-Hy
Publisher: American Chemical Society (ACS)
Date: 20-08-2008
DOI: 10.1021/JP801805P
Abstract: We present a number of near-exact, nonrelativistic, Born-Oppenheimer reference data sets for the parametrization of more approximate methods (such as DFT functionals). The data were obtained by means of the W4 ab initio computational thermochemistry protocol, which has a 95% confidence interval well below 1 kJ/mol. Our data sets include W4-08, which are total atomization energies of over 100 small molecules that cover varying degrees of nondynamical correlations, and DBH24-W4, which are W4 theory values for Truhlar's set of 24 representative barrier heights. The usual procedure of comparing calculated DFT values with experimental atomization energies is h ered by comparatively large experimental uncertainties in many experimental values and compounds errors due to deficiencies in the DFT functional with those resulting from neglect of relativity and finite nuclear mass. Comparison with accurate, explicitly nonrelativistic, ab initio data avoids these issues. We then proceed to explore the performance of B2x-PLYP-type double hybrid functionals for atomization energies and barrier heights. We find that the optimum hybrids for hydrogen-transfer reactions, heavy-atoms transfers, nucleophilic substitutions, and unimolecular and recombination reactions are quite different from one another: out of these subsets, the heavy-atom transfer reactions are by far the most sensitive to the percentages of Hartree-Fock-type exchange y and MP2-type correlation x in an (x, y) double hybrid. The (42,72) hybrid B2K-PLYP, as reported in a preliminary communication, represents the best compromise between thermochemistry and hydrogen-transfer barriers, while also yielding excellent performance for nucleophilic substitutions. By optimizing for best overall performance on both thermochemistry and the DBH24-W4 data set, however, we find a new (36,65) hybrid which we term B2GP-PLYP. At a slight expense in performance for hydrogen-transfer barrier heights and nucleophilic substitutions, we obtain substantially better performance for the other reaction types. Although both B2K-PLYP and B2GP-PLYP are capable of 2 kcal/mol quality thermochemistry, B2GP-PLYP appears to be the more robust toward nondynamical correlation and strongly polar character. We additionally find that double-hybrid functionals display excellent performance for such problems as hydrogen bonding, prototype late transition metal reactions, pericyclic reactions, prototype cumulene-polyacetylene system, and weak interactions.
How reliable is DFT in predicting relative energies of polycyclic aromatic hydrocarbon isomers? comparison of functionals from different rungs of jacob's ladder
Publisher: Wiley
Date: 17-11-2017
DOI: 10.1002/JCC.24669
Abstract: Density functional theory (DFT) is the only quantum-chemical avenue for calculating thermochemical/kinetic properties of large polycyclic aromatic hydrocarbons (PAHs) such as graphene nanoflakes. Using CCSD(T)/CBS PAH isomerization energies, we find that all generalized gradient approximation (GGA) and meta GGA DFT functionals have severe difficulties in describing isomerization energies in PAHs. The poor performance of these functionals is demonstrated by the following root-mean-square deviations (RMSDs) obtained for a database of C
Accurate Thermochemical and Kinetic Stabilities of C84 Isomers
Publisher: American Chemical Society (ACS)
Date: 24-04-2018
Abstract: Accurate double-hybrid density functional theory and isodesmic-type reaction schemes are utilized to report accurate estimates of the heats of formation (Δ
Basis set convergence of CCSD(T) equilibrium geometries using a large and diverse set of molecular structures
Publisher: AIP Publishing
Date: 12-09-2016
DOI: 10.1063/1.4962168
Abstract: We examine the basis set convergence of the CCSD(T) method for obtaining the structures of the 108 neutral first- and second-row species in the W4-11 database (with up to five non-hydrogen atoms). This set includes a total of 181 unique bonds: 75 H—X, 49 X—Y, 43 X=Y, and 14 X≡Y bonds (where X and Y are first- and second-row atoms). As reference values, geometries optimized at the CCSD(T)/aug′-cc-pV(6+d)Z level of theory are used. We consider the basis set convergence of the CCSD(T) method with the correlation consistent basis sets cc-pV(n+d)Z and aug′-cc-pV(n+d)Z (n = D, T, Q, 5) and the Weigend–Ahlrichs def2-n ZVPP basis sets (n = T, Q). For each increase in the highest angular momentum present in the basis set, the root-mean-square deviation (RMSD) over the bond distances is decreased by a factor of ∼4. For ex le, the following RMSDs are obtained for the cc-pV(n+d)Z basis sets 0.0196 (D), 0.0050 (T), 0.0015 (Q), and 0.0004 (5) Å. Similar results are obtained for the aug′-cc-pV(n+d)Z and def2-n ZVPP basis sets. The double-zeta and triple-zeta quality basis sets systematically and significantly overestimate the bond distances. A simple and cost-effective way to improve the performance of these basis sets is to scale the bond distances by an empirical scaling factor of 0.9865 (cc-pV(D+d)Z) and 0.9969 (cc-pV(T+d)Z). This results in RMSDs of 0.0080 (scaled cc-pV(D+d)Z) and 0.0029 (scaled cc-pV(T+d)Z) Å. The basis set convergence of larger basis sets can be accelerated via standard basis-set extrapolations. In addition, the basis set convergence of explicitly correlated CCSD(T)-F12 calculations is investigated in conjunction with the cc-pVnZ-F12 basis sets (n = D, T). Typically, one “gains” two angular momenta in the explicitly correlated calculations. That is, the CCSD(T)-F12/cc-pVnZ-F12 level of theory shows similar performance to the CCSD(T)/cc-pV(n+2)Z level of theory. In particular, the following RMSDs are obtained for the cc-pVnZ-F12 basis sets 0.0019 (D) and 0.0006 (T) Å. Overall, the CCSD(T)-F12/cc-pVDZ-F12 level of theory offers a stellar price-performance ratio and we recommend using it when highly accurate reference geometries are needed (e.g., in composite ab initio theories such as W4 and HEAT).
Potassium Poly(Heptazine Imide)
Publisher: Wiley
Date: 09-06-2020
Tailoring the capability of carbon nitride (C3N) nanosheets toward hydrogen storage upon light transition metal decoration
Publisher: IOP Publishing
Date: 21-12-2019
Abstract: To nurture the full potential of hydrogen (H
NLO Properties of Metallabenzene-Based Chromophores: A Time-Dependent Density Functional Study
Publisher: American Chemical Society (ACS)
Date: 28-05-2005
DOI: 10.1021/JP0443456
Abstract: The static and dynamic first hyperpolarizabilities for a series of substituted metallabenzene-based nonlinear optical (NLO) chromophores were determined by time-dependent density functional theory (TDDFT). The electronic excitation contributions to the first hyperpolarizability are rationalized in terms of the two-level model. The effects on the hyperpolarizabilities of (a) the metal center (Os, Ir, Pt) (b) the ligand environment (PH3, CO, Cl) (c) various donor and acceptor substituents (NH2, OH, Me, H, Cl, Br, I, COOMe, COOH, CN, NO2) and (d) the length of pi-conjugation were studied. Our calculations predict that metallabenzenes have significant second-order NLO susceptibilities, ranging from = 1.0 x 10(-29) to 5.6 x 10(-28) esu and from mu = 3.0 x 10(-47) to 1.1 x 10(-44) esu, that can be tuned by changing the metal center and/or ligand environment.
Remarkable improvement in hydrogen storage capacities of two-dimensional carbon nitride (g-C3N4) nanosheets under selected transition metal doping
Publisher: Elsevier BV
Date: 2020
Superior performance of the machine-learning GAP force field for fullerene structures
Publisher: Springer Science and Business Media LLC
Date: 22-01-2022
Comparative Study of Carbon Force Fields for the Simulation of Carbon Onions
Publisher: CSIRO Publishing
Date: 07-10-2021
DOI: 10.1071/CH21172
Abstract: We evaluate the performance of ten common carbon force fields for the interaction energies in double and triple layered carbon onions. In particular, we consider the C20@C60, C20@C80, C20@C180, C80@C240, C60@C240 and C240@C540 double-layer carbon onions and C60@C240@C540 and C80@C240@C540 triple-layered carbon onions. We consider the following carbon force fields: Tersoff, REBO-II, AIREBO, AIREBO-M, screened versions of Tersoff and REBO-II, LCBOP-I, 2015 and 2020 versions of ReaxFF, and the machine-learning GAP force field. We show that the ReaxFF force fields give the best performance for the interaction energies of the cabon onions relative to density functional theory interaction energies obtained at the PBE0-D3/def2-TZVP level of theory. We proceed to use the ReaxFF-15 force field to explore the interaction energies in a giant ten-layered carbon onion with a C60 core and show that the interaction energy between the outer layer and the inner layers increases linearly with the number of layers in the carbon onion (with a squared correlation coefficient of R2 = 0.9996). This linear increase in the stabilization energy with each consecutive layer may have important thermodynamic consequences for describing the formation and growth of large carbon onions.
Empowering hydrogen storage properties of haeckelite monolayers via metal atom functionalization
Publisher: Elsevier BV
Date: 08-2021
Experimental and Theoretical Study of the Chemical Network of the Hydrogenation of NO on Interstellar Dust Grains
Publisher: American Chemical Society (ACS)
Date: 30-05-2019
Dy3Al2(AlO4)3 ceramic nanogarnets: Sol-gel auto-combustion synthesis, characterization and joint experimental and computational structural analysis for electrochemical hydrogen storage performances
Publisher: Elsevier BV
Date: 05-2018
Atomization energies of the carbon clusters Cn(n= 2−10) revisited by means of W4 theory as well as density functional, Gn, and CBS methods
Publisher: Informa UK Limited
Date: 20-04-2009
Computational insights into the singlet–triplet energy gaps, ionization energies, and electron affinities for a diverse set of 812 small fullerenes (C20–C50)
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3CP01357J
Abstract: A thorough DFT investigation of over 800 small fullerenes reveals the ones with promising thermochemical properties for electronics applications.
Thermochemistry of the Smallest Hyperbolic Paraboloid Hydrocarbon: A High-Level Quantum Chemical Perspective
Publisher: MDPI AG
Date: 19-04-2023
DOI: 10.3390/C9020041
Abstract: [5.5.5.5]hexaene is a [12]annulene ring with a symmetrically bound carbon atom in its center. This is the smallest hydrocarbon with a hyperbolic paraboloid shape. [5.5.5.5]hexaene and related hydrocarbons are important building blocks in organic and materials chemistry. For ex le, penta-graphene—a puckered 2D allotrope of carbon—is comprised of similar repeating subunits. Here, we investigate the thermochemical and kinetic properties of [5.5.5.5]hexaene at the CCSD(T) level by means of the G4 thermochemical protocol. We find that this system is energetically stable relative to its isomeric forms. For ex le, isomers containing a phenyl ring with one or more acetylenic side chains are higher in energy by ∆H298 = 17.5–51.4 kJ mol−1. [5.5.5.5]hexaene can undergo skeletal inversion via a completely planar transition structure however, the activation energy for this process is ∆H‡298 = 249.2 kJ mol−1 at the G4 level. This demonstrates the high configurational stability of [5.5.5.5]hexaene towards skeletal inversion. [5.5.5.5]hexaene can also undergo a π-bond shift reaction which proceeds via a relatively low-lying transition structure with an activation energy of ∆H‡298 = 67.6 kJ mol−1. Therefore, this process is expected to proceed rapidly at room temperature.
Understanding and utilizing hardware transactional memory capacity
Publisher: ACM
Date: 22-06-2021
Geometries, interaction energies and complexation free energies of 18-crown-6 with neutral molecules
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CE02039A
Macromolecular approach for targeted radioimmunotherapy in non-Hodgkin's lymphoma
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CC06603A
Abstract: Polymers are an attractive anchoring platform for the synthesis of radioimmunoconjugates.
Comprehensive theoretical study of the correlation between the energetic and thermal stabilities for the entire set of 1812 C60 isomers
Publisher: AIP Publishing
Date: 11-08-2022
DOI: 10.1063/5.0100612
Abstract: The thermal stability of fullerenes plays a fundamental role in their synthesis and in their thermodynamic and kinetic properties. Here, we perform extensive molecular dynamics (MD) simulations using an accurate machine-learning-based Gaussian Approximation Potential (GAP-20) force field to investigate the energetic and thermal properties of the entire set of 1812 C60 isomers. Our MD simulations predict a comprehensive and quantitative correlation between the relative isomerization energy distribution of the C60 isomers and their thermal fragmentation temperatures. We find that the 1812 C60 isomers span over an energetic range of over 400 kcal mol−1, where the majority of isomers (∼85%) lie in the range between 90 and 210 kcal mol−1 above the most stable C60-Ih buckminsterfullerene. Notably, the MD simulations show a clear statistical correlation between the relative energies of the C60 isomers and their fragmentation temperature. The maximum fragmentation temperature is 4800 K for the C60-Ih isomer and 3700 K for the energetically least stable isomer, where nearly 80% of isomers lie in a temperature window of 4000–4500 K. In addition, an Arrhenius-based approach is used to map the timescale gap between simulation and experiment and establish a connection between the MD simulations and fragmentation temperatures.
A Systematic Exploration of B–F Bond Dissociation Enthalpies of Fluoroborane-Type Molecules at the CCSD(T)/CBS Level
Publisher: MDPI AG
Date: 28-07-2023
DOI: 10.3390/MOLECULES28155707
Abstract: Fluoroborane-type molecules (R1R2B–F) are of interest in synthetic chemistry, but to date, apart from a handful of small species (such as H2BF, HBF2, and BF3), little is known concerning the effect of substituents in governing the strength of the B–F bonds of such species toward homolytic dissociation in the gas phase. In this study, we have calculated the bond dissociation enthalpies (BDEs) of thirty unique B–F bonds at the CCSD(T)/CBS level using the high-level W1w thermochemical protocol. The B–F bonds in all species considered are very strong, ranging from 545.9 kJ mol−1 in (H2B)2B–F to 729.2 kJ mol−1 HBF2. Nevertheless, these BDEs still vary over a wide range of 183.3 kJ mol−1. The structural properties that affect the BDEs are examined in detail, and the homolytic BDEs are rationalized based on molecule stabilization enthalpies and radical stabilization enthalpies. Since polar B–F bonds may represent a challenging test case for density functional theory (DFT) methods, we proceed to examine the performance of a wide range of DFT methods across the rungs of Jacob′s Ladder for their ability to compute B–F BDEs. We find that only a handful of DFT methods can reproduce the CCSD(T)/CBS BDEs with mean absolute deviations (MADs) below the threshold of chemical accuracy (i.e., with average deviations below 4.2 kJ mol−1). The only functionals capable of achieving this feat were (MADs given in parentheses): ωB97M-V (4.0), BMK (3.5), DSD-BLYP (3.8), and DSD-PBEB95 (1.8 kJ mol−1).
Study of dual encapsulation possibility of hydrophobic and hydrophilic drugs into a nanocarrier based on bio-polymer coated graphene oxide using density functional theory, molecular dynamics simulatio
Publisher: Elsevier BV
Date: 07-2018
A Coordination Controlled Aryl–Halide Oxidative Addition to Platinum
Publisher: Wiley
Date: 28-09-2009
CCSD(T) Rotational Constants for Highly Challenging C5H2 Isomers—A Comparison between Theory and Experiment
Publisher: MDPI AG
Date: 09-09-2023
The reaction of the benzene cation with acetylenes for the growth of PAHs in the interstellar medium
Publisher: Elsevier BV
Date: 03-2014
Pinning the most stable HxCyOz isomers in space by means of high-level theoretical procedures
Publisher: Elsevier BV
Date: 06-2014
Covalency and Ionicity Do Not Oppose Each Other-Relationship Between Si−O Bond Character and Basicity of Siloxanes
Publisher: Wiley
Date: 21-09-2018
Abstract: Covalency and ionicity are orthogonal rather than antipodal concepts. We demonstrate for the case of siloxane systems [R
Fullerenes Pose a Strain on Hybrid Density Functional Theory
Publisher: American Chemical Society (ACS)
Date: 19-07-2022
Abstract: The computational modeling of fullerenes plays a fundamental role in designing low-dimension carbon nanostructures. Nevertheless, the relative energies of fullerenes larger than C
Basis set convergence of high-order coupled cluster methods up to CCSDTQ567 for a highly multireference molecule
Publisher: Elsevier BV
Date: 12-2019
Pristine Graphene as a Racemization Catalyst for Axially Chiral BINOL
Publisher: Wiley
Date: 14-07-2020
The adsorption and migration behavior of divalent metals (Mg, Ca, and Zn) on pristine and defective graphene
Publisher: Elsevier BV
Date: 08-2020
Borane–Lewis Base Complexes as Homolytic Hydrogen Atom Donors
Publisher: Wiley
Date: 14-06-2010
Abstract: Radical stabilization energies (RSE)s have been calculated for a variety of boryl radicals complexed to Lewis bases at the G3(MP2)-RAD level of theory. These are referenced to the B-H bond dissociation energy (BDE) in BH(3) determined at W4.3 level. High RSE values (and thus low BDE(B-H) values) have been found for borane complexes of a variety of five- and six-membered ring heterocycles. Variations of RSE values have been correlated with the strength of Lewis acid-Lewis base complex formation at the boryl radical stage. The analysis of charge- and spin-density distributions shows that spin delocalization in the boryl radical complexes constitutes one of the mechanisms of radical stabilization.
Structure-Activity Studies of Semiochemicals from the Spider Orchid Caladenia plicata for Sexual Deception
Publisher: Springer Science and Business Media LLC
Date: 17-03-2018
DOI: 10.1007/S10886-018-0946-0
Abstract: Sexually deceptive orchids attract specific pollinators by mimicking insect sex pheromones. Normally this mimicry is very specific and identical compounds have been identified from orchids and matching females of the pollinators. In this study, we conduct a detailed structure-activity investigation on isomers of the semiochemicals involved in the sexual attraction of the male pollinator of the spider orchid Caladenia plicata. This orchid employs an unusual blend of two biosynthetically unrelated compounds, (S)-β-citronellol and 2-hydroxy-6-methylacetophenone, to lure its Zeleboria sp. thynnine wasp pollinator. We show that the blend is barely attractive when (S)-β-citronellol is substituted with its enantiomer, (R)-β-citronellol. Furthermore, none of the nine-possible alternative hydroxy-methylacetophenone regioisomers of the natural semiochemical are active when substituted for the natural 2-hydroxy-6-methylacetophenone. Our results were surprising given the structural similarity between the active compound and some of the analogues tested, and results from previous studies in other sexually deceptive orchid/wasp systems where substitution with analogues was possible. Interestingly, high-level ab initio and density functional theory calculations of the hydroxy-methylacetophenones revealed that the active natural isomer, 2-hydroxy-6-methylacetophenone, has the strongest intramolecular hydrogen bond of all regioisomers, which at least in part may explain the specific activity.
Accurate quantum chemical energies for tetrapeptide conformations: why MP2 data with an insufficient basis set should be handled with caution
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP00057E
Abstract: High-level quantum chemical calculations have been carried out for biologically-relevant conformers of tetrapeptides. Our results indicate potential problems if the widely-applied MP2 approach is used in such situations with basis sets of insufficient size. Efficient alternatives are discussed.
Energetic and spectroscopic properties of the low-lying C7 H2 isomers: A high-level: Ab initio perspective
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CP02848B
Abstract: We report here nine low-lying isomers of C 7 H 2 , which lie within 1 eV, investigated with high-level ab initio methods.
Correction to “The High Performance of Choline Arginate for Biomass Pretreatment Is Due to Remarkably Strong Hydrogen Bonding by the Anion”
Publisher: American Chemical Society (ACS)
Date: 05-06-2020
Toward Improved Performance of All-Organic Nitroxide Radical Batteries with Ionic Liquids: A Theoretical Perspective
Publisher: American Chemical Society (ACS)
Date: 02-2019
π–π Catalysis in Carbon Flatland—Flipping [8]Annulene on Graphene
Publisher: Wiley
Date: 21-01-2021
Abstract: Noncovalent interactions are an integral part of the modern catalysis toolbox. Although stronger noncovalent interactions such as hydrogen bonding are commonly the main driving force of catalysis, π–π interactions typically provide smaller additional stabilizations, for ex le, to afford selectivity enhancements. Here, it is shown computationally that pristine graphene flakes may efficiently catalyze the skeletal inversions of various benzannulated cyclooctatetraene derivatives, providing an ex le of a catalytic process driven solely by π–π stacking interactions. Hereby, the catalytic effect results from disproportionate shape complementarity between catalyst and transition structure compared with catalyst and reactant. An energy decomposition analysis reveals electrostatic and, especially with increasing system size, to a larger extent, dispersion interactions as the origin of stabilization.
Highly accurate CCSD(T) homolytic Al–H bond dissociation enthalpies – chemical insights and performance of density functional theory
Publisher: CSIRO Publishing
Date: 2023
DOI: 10.1071/CH23042
Highly Accurate CCSDT(Q)/CBS Reaction Barrier Heights for a Diverse Set of Transition Structures: Basis Set Convergence and Cost-Effective Approaches for Estimating Post-CCSD(T) Contributions
Publisher: American Chemical Society (ACS)
Date: 16-07-2019
Abstract: The ability to accurately calculate reaction barrier heights is of central importance to many areas of chemistry. We report an extensive study examining the basis set convergence of post-CCSD(T) contributions (up to CCSDT(Q)) for a erse set of 28 reaction barrier heights. In contrast to previous studies, we focus here on larger transition structures (TSs) involving 4-7 non-hydrogen atoms. The set of reaction barrier heights includes pericyclic, bipolar cycloaddition, cycloreversion, and multiple-proton transfer reactions. We find that in most cases post-CCSD(T) contributions converge rapidly toward the basis set limit, such that even double-ζ and truncated double-ζ basis sets provide useful estimates of the T-(T) and (Q) contributions, respectively. In addition, we find that due to the tendency of these small basis sets to systematically underestimate the T-(T) and (Q) components, scaling is an effective approach for improving performance. For ex le, scaling the T-(T)/cc-pVDZ contribution by 1.25 results in an RMSD of merely 0.4 kJ mol
The lowest singlet-triplet excitation energy of BN: A converged coupled cluster perspective
Publisher: AIP Publishing
Date: 12-10-2006
DOI: 10.1063/1.2352752
Abstract: The notoriously small XΠ3−aΣ+1 excitation energy of the BN diatomic has been calculated using high-order coupled cluster methods. Convergence has been established in both the one-particle basis set and the coupled cluster expansion. Explicit inclusion of connected quadruple excitations T̂4 is required for even semiquantitative agreement with the limit value, while connected quintuple excitations T̂5 still have an effect of about 60cm−1. Still higher excitations only account for about 10cm−1. Inclusion of inner-shell correlation further reduces Te by about 60cm−1 at the CCSDT, and 85cm−1 at the CCSDTQ level. Our best estimate, Te=183±40cm−1, is in excellent agreement with earlier calculations and experiment, albeit with a smaller (and conservative) uncertainty. The dissociation energy of BN(XΠ3) is De=105.74±0.16kcal∕mol and D0=103.57±0.16kcal∕mol.
Perylene bisimide cyclophanes as receptors for planar transition structures – catalysis of stereoinversions by shape-complementarity and noncovalent π–π interactions
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1QO00755F
Abstract: Perylene bisimide cyclophanes, ideal receptors for planar aromatic compounds, act as π–π catalysts by stabilizing shape-complementary stereoinversion transition structures.
Elemental substitution of two-dimensional transition metal dichalcogenides (MoSe2 and MoTe2)
Publisher: American Chemical Society (ACS)
Date: 30-09-2019
DOI: 10.1021/ACSSENSORS.9B01044
Abstract: The quest for a suitable material with the potential of capturing toxic nitrogen-containing gases (NH
NH and NCl homolytic bond dissociation energies and radical stabilization energies: An assessment of theoretical procedures through comparison with benchmark‐quality W2w data
Publisher: Wiley
Date: 08-08-2011
DOI: 10.1002/QUA.23210
O(3P) + CO2 Collisions at Hyperthermal Energies: Dynamics of Nonreactive Scattering, Oxygen Isotope Exchange, and Oxygen-Atom Abstraction
Publisher: American Chemical Society (ACS)
Date: 20-12-2011
DOI: 10.1021/JP2080379
Abstract: The dynamics of O((3)P) + CO(2) collisions at hyperthermal energies were investigated experimentally and theoretically. Crossed-molecular-beams experiments at = 98.8 kcal mol(-1) were performed with isotopically labeled (12)C(18)O(2) to distinguish products of nonreactive scattering from those of reactive scattering. The following product channels were observed: elastic and inelastic scattering ((16)O((3)P) + (12)C(18)O(2)), isotope exchange ((18)O + (16)O(12)C(18)O), and oxygen-atom abstraction ((18)O(16)O + (12)C(18)O). Stationary points on the two lowest triplet potential energy surfaces of the O((3)P) + CO(2) system were characterized at the CCSD(T)/aug-cc-pVTZ level of theory and by means of W4 theory, which represents an approximation to the relativistic basis set limit, full-configuration-interaction (FCI) energy. The calculations predict a planar CO(3)(C(2v), (3)A'') intermediate that lies 16.3 kcal mol(-1) (W4 FCI excluding zero point energy) above reactants and is approached by a C(2v) transition state with energy 24.08 kcal mol(-1). Quasi-classical trajectory (QCT) calculations with collision energies in the range 23-150 kcal mol(-1) were performed at the B3LYP/6-311G(d) and BMK/6-311G(d) levels. Both reactive channels observed in the experiment were predicted by these calculations. In the isotope exchange reaction, the experimental center-of-mass (c.m.) angular distribution, T(θ(c.m.)), of the (16)O(12)C(18)O products peaked along the initial CO(2) direction (backward relative to the direction of the reagent O atoms), with a smaller isotropic component. The product translational energy distribution, P(E(T)), had a relatively low average of = 35 kcal mol(-1), indicating that the (16)O(12)C(18)O products were formed with substantial internal energy. The QCT calculations give c.m. P(E(T)) and T(θ(c.m.)) distributions and a relative product yield that agree qualitatively with the experimental results, and the trajectories indicate that exchange occurs through a short-lived CO(3)* intermediate. A low yield for the abstraction reaction was seen in both the experiment and the theory. Experimentally, a fast and weak (16)O(18)O product signal from an abstraction reaction was observed, which could only be detected in the forward direction. A small number of QCT trajectories leading to abstraction were observed to occur primarily via a transient CO(3) intermediate, albeit only at high collision energies (149 kcal mol(-1)). The oxygen isotope exchange mechanism for CO(2) in collisions with ground state O atoms is a newly discovered pathway through which oxygen isotopes may be cycled in the upper atmosphere, where O((3)P) atoms with hyperthermal translational energies can be generated by photodissociation of O(3) and O(2).
Heat of formation for C60 by means of the G4(MP2) thermochemical protocol through reactions in which C60 is broken down into corannulene and sumanene
Publisher: Elsevier BV
Date: 2016
Formation of distinct iron hydrides via mechanistic divergence in directed C–H Bond activation of aryl ketones, esters and amides
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2CC04394G
Abstract: Chelation vs. metal-ring walking: directing groups determine the mechanism of C–H bond activation by an iron(0) PC (NHC) P pincer complex.
Catalysis by Pure Graphene—From Supporting Actor to Protagonist through Shape Complementarity
Publisher: American Chemical Society (ACS)
Date: 09-08-2019
Abstract: In most catalytic applications, graphene is either functionalized or acts as the catalyst support. DFT calculations show on the ex le of the racemizations of binaphthyl compounds that pure unmodified graphene can directly catalyze chemical processes through stabilizing noncovalent π-π interactions resulting from shape complementarity between transition structures and catalyst.
Model for the Exceptional Reactivity of Peroxiredoxins 2 and 3 with Hydrogen Peroxide
Publisher: Elsevier BV
Date: 05-2011
Deciphering the exceptional selectivity of semipinacol rearrangements in cis-fused β-lactam diols using high-level quantum chemical methods
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8QO01092G
Abstract: The semipinacol rearrangement mechanism in cis -fused β-lactam diols has been found to kinetically and thermodynamically favor acyl migration. The semipinacol rearrangement was also investigated for trans -fused β-lactam diol, in which the reversed selectivity that favors the alkyl migration was observed.
An extended N-H bond, driven by a conserved second-order interaction, orients the flavin N5 orbital in cholesterol oxidase
Publisher: Springer Science and Business Media LLC
Date: 18-01-2017
DOI: 10.1038/SREP40517
Abstract: The protein microenvironment surrounding the flavin cofactor in flavoenzymes is key to the efficiency and ersity of reactions catalysed by this class of enzymes. X-ray diffraction structures of oxidoreductase flavoenzymes have revealed recurrent features which facilitate catalysis, such as a hydrogen bond between a main chain nitrogen atom and the flavin redox center (N5). A neutron diffraction study of cholesterol oxidase has revealed an unusual elongated main chain nitrogen to hydrogen bond distance positioning the hydrogen atom towards the flavin N5 reactive center. Investigation of the structural features which could cause such an unusual occurrence revealed a positively charged lysine side chain, conserved in other flavin mediated oxidoreductases, in a second shell away from the FAD cofactor acting to polarize the peptide bond through interaction with the carbonyl oxygen atom. Double-hybrid density functional theory calculations confirm that this electrostatic arrangement affects the N-H bond length in the region of the flavin reactive center. We propose a novel second-order partial-charge interaction network which enables the correct orientation of the hydride receiving orbital of N5. The implications of these observations for flavin mediated redox chemistry are discussed.
How large are post-CCSD(T) contributions to the total atomization energies of medium-sized alkanes?
Publisher: Elsevier BV
Date: 02-2016
Performance of local G4(MP2) composite ab initio procedures for fullerene isomerization energies
Publisher: Elsevier BV
Date: 11-2022
Celebrating Professor Graham Chandler's 80th Birthday
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CHV71N4_FO
Effect of Substituents on the Strength of N–X (X = H, F, and Cl) Bond Dissociation Energies: A High-Level Quantum Chemical Study
Publisher: American Chemical Society (ACS)
Date: 06-05-2011
DOI: 10.1021/JP203108E
Abstract: The effect of substituents on the strength of N-X (X = H, F, and Cl) bonds has been investigated using the high-level W2w thermochemical protocol. The substituents have been selected to be representative of the key functional groups that are likely to be of biological, synthetic, or industrial importance for these systems. We interpreted the effects through the calculation of relative N-X bond dissociation energies (BDE) or radical stabilization energies (RSE(NX)). The BDE and RSE(NX) values depend on stabilizing/destabilizing effects in both the reactant molecule and the product radical of the dissociation reactions. To assist us in the analysis of the substituent effects, a number of additional thermochemical quantities have been introduced, including molecule stabilization energies (MSE(NX)). We find that the RSE(NH) values are (a) increased by electron-donating alkyl substituents or the vinyl substituent, (b) increased in imines, and (c) decreased by electron-withdrawing substituents such as CF(3) and carbonyl moieties or through protonation. A different picture emerges when considering the RSE(NF) and RSE(NCl) values because of the electronegativities of the halogen atoms. The RSE(NX)s differ from the RSE(NH) values by an amount related to the stabilization of the N-halogenated molecules and given by MSE(NX). We find that substituents that stabilize/destabilize the radicals also tend to stabilize/destabilize the N-halogenated molecules. As a result, N-F- and N-Cl-containing molecules that include alkyl substituents or correspond to imines are generally associated with RSE(NF) and RSE(NCl) values that are less positive or more negative than the corresponding RSE(NH). In contrast, N-F- and N-Cl-containing molecules that include electron-withdrawing substituents or are protonated are generally associated with RSE(NF) and RSE(NCl) values that are more positive or less negative than the corresponding RSE(NH).
Quantum mechanical thermochemical predictions 100 years after the Schrödinger equation
Publisher: Elsevier
Date: 2022
Planarization of negatively curved [7]circulene on a graphene monolayer
Publisher: Elsevier BV
Date: 05-2023
A Computational Investigation of the Uncatalysed and Water-Catalysed Acyl Rearrangements in Ingenol Esters
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CH17501
Abstract: Ingenol esters have been identified as potent anticancer and HIV latency reversing agents. Ingenol-3-angelate was recently approved as a topical treatment for precancerous actinic keratosis skin lesions. It was found, however, that ingenol esters can undergo a series of acyl rearrangements, which may affect their biological potency and the shelf-life of drug formulations. We use double-hybrid density functional theory to explore the mechanisms for the uncatalysed and water-catalysed acyl migrations in a model ingenol ester. The uncatalysed reaction may proceed either via a concerted mechanism or via a stepwise mechanism that involves a chiral orthoester intermediate. We find that the stepwise pathway is kinetically preferred by a significant amount of ΔΔH‡298 = 44.5 kJ mol−1. The uncatalysed 3-O-acyl to 5-O-acyl and 5-O-acyl to 20-O-acyl stepwise rearrangements involve cyclisation and ring-opening steps, both concomitant with a proton transfer. We find that the ring-opening step is the rate-determining step for both rearrangements, with reaction barrier heights of ΔH‡298 = 251.6 and 177.1 kJ mol−1 respectively. The proton transfers in the cyclisation and ring-opening steps may be catalysed by a water molecule. The water catalyst reduces the reaction barrier heights of these steps by over 90 kJ mol−1.
Can DFT and ab initio methods describe all aspects of the potential energy surface of cycloreversion reactions?
Publisher: Informa UK Limited
Date: 15-09-2015
Carnosine and Carcinine Derivatives Rapidly React with Hypochlorous Acid to Form Chloramines and Dichloramines
Publisher: American Chemical Society (ACS)
Date: 29-01-2019
DOI: 10.1021/ACS.CHEMRESTOX.8B00363
Abstract: Hypochlorous acid (HOCl) is a highly reactive, toxic species generated by neutrophils via the action of myeloperoxidase in order to destroy invading pathogens. However, when HOCl is produced inappropriately, it can damage host tissue and proteins and plays a role in the initiation and progression of disease. Carnosine, a peptide of β-alanine and histidine, has been shown to react rapidly with HOCl yielding monochloramines and can undergo intramolecular transchlorination. The current study examines the kinetics and pH dependence of the reactions of carnosine and novel structural derivatives with HOCl and the occurrence of intra- and intermolecular transchlorination processes. We demonstrate that the transchlorination reactions of carnosine are pH dependent, with intramolecular transfer favored at higher pH. Carcinine, having a structure identical to carnosine though lacking the carboxylic acid group of the histidine residue, reacts with HOCl and forms monochloramines though intramolecular transfer reactions are not observed, and this is supported by computational modeling. Novel analogues with one (carnosine+1) and two (carnosine+2) methylene groups in the alkyl chain of the β-alanine react with HOCl to yield monochloramines that undergo transchlorinations to yield a mixture of mono- and dichloramines. The latter are stable over 24 h. The ability of carnosine and derivatives to react rapidly with HOCl to give long-lived, poorly reactive, species may prevent damage to proteins and other targets at sites of inflammation.
Stable room-temperature molecular negative differential resistance based on molecule-electrode interface chemistry
Publisher: American Chemical Society (ACS)
Date: 26-08-2004
DOI: 10.1021/JA049584L
Abstract: We show reproducible, stable negative differential resistance (NDR) at room temperature in molecule-controlled, solvent-free devices, based on reversible changes in molecule-electrode interface properties. The active component is the cyclic disulfide end of a series of molecules adsorbed onto mercury. As this active component is reduced, the Hg-molecule contact is broken, and an insulating barrier at the molecule-electrode interface is formed. Therefore, the alignment of the molecular energy levels, relative to the Fermi levels of the electrodes, is changed. This effect results in a decrease in the current with voltage increase as the reduction process progresses, leading to the so-called NDR behavior. The effect is reproducible and repeatable over more than 50 scans without any reduction in the current. The stability of the system, which is in the "solid state" except for the Hg, is due to the molecular design where long alkyl chains keep the molecules aligned with respect to the Hg electrode, even when they are not bound to it any longer.
The quest for the carbene bent-pentadiynylidene isomer of C5 H2
Publisher: Elsevier BV
Date: 11-2018
Benchmark atomization energy of ethane: Importance of accurate zero-point vibrational energies and diagonal Born–Oppenheimer corrections for a ‘simple’ organic molecule
Publisher: Elsevier BV
Date: 06-2007
Extensive Redox Non-Innocence in Iron Bipyridine-Diimine Complexes: a Combined Spectroscopic and Computational Study
Publisher: American Chemical Society (ACS)
Date: 17-11-2021
High-resolution structures of cholesterol oxidase in the reduced state provide insights into redox stabilization
Publisher: International Union of Crystallography (IUCr)
Date: 22-11-2014
DOI: 10.1107/S139900471402286X
Abstract: Cholesterol oxidase (CO) is a flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. The reductive half reaction occurs via a hydride transfer from the substrate to the FAD cofactor. The structures of CO reduced with dithionite under aerobic conditions and in the presence of the substrate 2-propanol under both aerobic and anaerobic conditions are presented. The 1.32 Å resolution structure of the dithionite-reduced enzyme reveals a sulfite molecule covalently bound to the FAD cofactor. The isoalloxazine ring system displays a bent structure relative to that of the oxidized enzyme, and alternate conformations of a triad of aromatic residues near to the cofactor are evident. A 1.12 Å resolution anaerobically trapped reduced enzyme structure in the presence of 2-propanol does not show a similar bending of the flavin ring system, but does show alternate conformations of the aromatic triad. Additionally, a significant difference electron-density peak is observed within a covalent-bond distance of N5 of the flavin moiety, suggesting that a hydride-transfer event has occurred as a result of substrate oxidation trapping the flavin in the electron-rich reduced state. The hydride transfer generates a tetrahedral geometry about the flavin N5 atom. High-level density-functional theory calculations were performed to correlate the crystallographic findings with the energetics of this unusual arrangement of the flavin moiety. These calculations suggest that strong hydrogen-bond interactions between Gly120 and the flavin N5 centre may play an important role in these structural features.
The Melatonin Conformer Space: Benchmark and Assessment of Wave Function and DFT Methods for a Paradigmatic Biological and Pharmacological Molecule
Publisher: American Chemical Society (ACS)
Date: 03-2013
DOI: 10.1021/JP312644T
Abstract: Reference quality conformational energies have been obtained for the 52 unique conformers of melatonin by means of explicitly correlated ab initio methods as well as the ccCA composite method. These data have then been used to evaluate more approximate methods, including a variety of density functionals both on their own and paired with various empirical dispersion corrections. Owing to the presence of internal contacts of the C-H···O and C-H···N variety, basis set convergence is much slower than for alkane conformers, for ex le, and basis sets of aug-cc-pVQZ or def2-QZVP quality seem to be required to obtain firm estimates of the basis set limit. Not just HF, but also many DFT functionals, will transpose the two lowest conformers unless empirical dispersion corrections are added. Somewhat surprisingly, many DFT functionals reproduce the reference data to fairly high accuracy when combined with the D3BJ empirical dispersion correction or the "nonlocal" Vydrov-Van Voorhis dispersion model. The two best performers including dispersion corrections are the double hybrids DSD-PBEP86-D3BJ and B2GP-PLYP-D if no such correction is permitted, then M06-2X puts in the best performance. Of lower-cost ab initio-like models, MP2.5 yields the best performance, followed by SCS-MP2.
Reversible hydrogen storage properties of defect-engineered C4N nanosheets under ambient conditions
Publisher: Elsevier BV
Date: 11-2019
Sneaking up on the Criegee intermediate from below: Predicted photoelectron spectrum of the CH2OO- anion and W3-F12 electron affinity of CH2OO
Publisher: Elsevier BV
Date: 10-2013
Graphene‐induced planarization of cyclooctatetraene derivatives
Publisher: Wiley
Date: 22-10-2021
DOI: 10.1002/JCC.26774
Abstract: Stable equilibrium compounds containing a planar antiaromatic cyclooctatetraene (COT) ring are promising candidates for organic electronic devices such as organic semiconductor transistors. The planarization of COT by incorporation into rigid planar π‐systems, as well as by oxidation or reduction has attracted considerable attention in recent years. Using dispersion‐corrected density functional theory calculations, we explore an alternative approach of planarizing COT derivatives by adsorption onto graphene. We show that strong π–π stacking interactions between graphene and COT derivatives induce a planar structure with an antiaromatic central COT ring. In addition to being reversible, this strategy provides a novel approach for planarizing COT without the need for incorporation into a rigid structure, atomic substitution, oxidation, or reduction.
Computational Design of Effective, Bioinspired HOCl Antioxidants: The Role of Intramolecular Cl+ and H+ Shifts
Publisher: American Chemical Society (ACS)
Date: 13-11-2012
DOI: 10.1021/JA309273N
Abstract: The enzyme myeloperoxidase generates significant amounts of hypochlorous acid (HOCl) at sites of inflammation to inflict oxidative damage upon invading pathogens. However, excessive production of this potent oxidant is associated with numerous inflammatory diseases. Recent kinetic measurements suggest that the endogenous antioxidant carnosine is an effective HOCl scavenger. On the basis of computational modeling, we suggest a possible mechanism for this antioxidant activity. We find that a unique structural relationship between three adjacent functional groups (imidazole, carboxylic acid, and terminal amine) enables an intramolecular chlorine transfer to occur. In particular, two sequential proton shifts are coupled with a Cl(+) shift converting the kinetically favored product (chlorinated at the imidazole nitrogen) into the thermodynamically favored product (chlorinated at the terminal amine) effectively trapping the chlorine. We proceed to design systems that share similar structural features to those of carnosine but with even greater HOCl-scavenging capabilities.
Assessment of DLPNO‐CCSD (T)‐F12 and its use for the formulation of the low‐cost and reliable L‐W1X composite method
Publisher: Wiley
Date: 16-06-2022
DOI: 10.1002/JCC.26892
Abstract: In the present study, we have investigated the performance of RIJCOSX DLPNO‐CCSD(T)‐F12 methods for a wide range of systems. Calculations with a high‐accuracy option [“DefGrid3 RIJCOSX DLPNO‐CCSD(T 1 )‐F12”] extrapolated to the complete‐basis‐set limit using the maug‐cc‐pV[D+d,T+d]Z basis sets provides fairly good agreements with the canonical CCSD(T)/CBS reference for a erse set of thermochemical and kinetic properties [with mean absolute deviations (MADs) of ~1–2 kJ mol −1 except for atomization energies]. On the other hand, the low‐cost “RIJCOSX DLPNO‐CCSD(T)‐F12D” option leads to substantial deviations for certain properties, notably atomization energies (MADs of up to tens of kJ mol −1 ). With the high‐accuracy CBS approach, we have formulated the L‐W1X method, which further includes a low‐cost core–valence plus scalar‐relativistic term. It shows generally good accuracy. For improved accuracies in specific cases, we advise replacing maug‐cc‐pV( n +d)Z with jun‐cc‐pV( n +d)Z for the calculation of electron affinities, and using well‐constructed isodesmic‐type reactions to obtain atomization energies. For medium‐sized systems, DefGrid3 RIJCOSX DLPNO‐CCSD(T 1 )‐F12 calculations are several times faster than the corresponding canonical computation the use of the local approximations (RIJCOSX and DLPNO) leads to a better scaling than that for the canonical calculation (from ~6–7 down to ~2–4 for our test systems). Thus, the DefGrid3 RIJCOSX DLPNO‐CCSD(T 1 )‐F12 method, and the L‐W1X protocol that based on it, represent a useful means for obtaining accurate thermochemical quantities for larger systems.
Scavenging properties of yttrium nitride monolayer towards toxic sulfur gases
Publisher: Elsevier BV
Date: 2021
Correlation between the energetic and thermal properties of C40 fullerene isomers: An accurate machine-learning force field study
Publisher: Elsevier BV
Date: 04-2022
Evaluating communication for resident participation in an aged care facility
Publisher: Informa UK Limited
Date: 2005
Can force fields developed for carbon nanomaterials describe the isomerization energies of fullerenes?
Publisher: Elsevier BV
Date: 09-2021
Sulphuric acid-catalysed formation of hemiacetal from glyoxal and ethanol
Publisher: Elsevier BV
Date: 05-2017
Tightening the Screws: The Importance of Tight d Functions in Coupled-Cluster Calculations up to the CCSDT(Q) Level
Publisher: American Chemical Society (ACS)
Date: 07-11-2022
Abstract: It is well established that the basis set convergence of the correlation consistent (cc-pV
Can Popular DFT Approximations and Truncated Coupled Cluster Theory Describe the Potential Energy Surface of the Beryllium Dimer?
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/CH18269
Abstract: The potential energy surface (PES) of the ground state of the beryllium dimer poses a significant challenge for high-level ab initio electronic structure methods. Here, we present a systematic study of basis set effects over the entire PES of Be2 calculated at the full configuration interaction (FCI) level. The reference PES is calculated at the valence FCI/cc-pV{5,6}Z level of theory. We find that the FCI/cc-pV{T,Q}Z basis set extrapolation reproduces the shape of the FCI/cc-pV{5,6}Z PES as well as the binding energy and vibrational transition frequencies to within ~10 cm−1. We also use the FCI/cc-pV{5,6}Z PES to evaluate the performance of truncated coupled cluster methods (CCSD, CCSD(T), CCSDT, and CCSDT(Q)) and contemporary density functional theory methods (DFT) methods for the entire PES of Be2. Of the truncated coupled cluster methods, CCSDT(Q)/cc-pV{5,6}Z provides a good representation of the FCI/cc-pV{5,6}Z PES. The GGA functionals, as well as the HGGA and HMGGA functionals with low percentages of exact exchange tend to severely overbind the Be2 dimer, whereas BH& HLYP and M06-HF tend to underbind it. Range-separated DFT functionals tend to underbind the dimer. Double-hybrid DFT functionals show surprisingly good performance, with DSD-PBEP86 being the best performer. Møller–Plesset perturbation theory converges smoothly up to fourth order however, fifth-order corrections have practically no effect on the PES.
Effective basis set extrapolations for CCSDT, CCSDT(Q), and CCSDTQ correlation energies
Publisher: AIP Publishing
Date: 08-07-2020
DOI: 10.1063/5.0011674
Abstract: It is well established that extrapolating the coupled-cluster single double triple [CCSD and (T)] correlation energies using empirically motivated extrapolation exponents can accelerate the basis set convergence. Here, we consider the extrapolation of coupled-cluster expansion terms beyond the CCSD(T) level to the complete basis set (CBS) limit. We obtain reference CCSDT–CCSD(T) [T3–(T)], CCSDT(Q)–CCSDT [(Q)], and CCSDTQ–CCSDT(Q) [T4–(Q)] contributions from cc-pV{5,6}Z extrapolations for a erse set of 16 first- and second-row systems. We use these basis-set limit results to fit extrapolation exponents in conjunction with the cc-pV{D,T}Z, cc-pV{T,Q}Z, and cc-pV{Q,5}Z basis set pairs. The optimal extrapolation exponents result in noticeable improvements in performance (relative to α = 3.0) in conjunction with the cc-pV{T,Q}Z basis set pair however, smaller improvements are obtained for the other basis sets. These results confirm that the basis sets and basis set extrapolations used for obtaining post-CCSD(T) components in composite thermochemical theories such as Weizmann-4 and HEAT are sufficiently close to the CBS limit for attaining sub-kJ/mole accuracy. The fitted extrapolation exponents demonstrate that the T3–(T) correlation component converges more slowly to the CBS limit than the (Q) and T4 terms. A systematic investigation of the effect of diffuse functions shows that it diminishes (i) in the order T3–(T) & (Q) & T4–(Q) and (ii) with the size of the basis set. Importantly, we find that diffuse functions tend to systematically reduce the T3–(T) contribution but systematically increases the (Q) contribution. Thus, the use of the cc-pVnZ basis sets benefits from a certain degree of error cancellation between these two components.
Inversion and rotation processes involving non-planar aromatic compounds catalyzed by extended polycyclic aromatic hydrocarbons
Publisher: Elsevier BV
Date: 10-2014
Post-CCSD(T) ab Initio Thermochemistry of Halogen Oxides and Related Hydrides XOX, XOOX, HOX, XOn, and HXOn (X = F, Cl), and Evaluation of DFT Methods for These Sys
Publisher: American Chemical Society (ACS)
Date: 21-01-2009
DOI: 10.1021/JP8087435
Abstract: Benchmark-quality W4 (and related) thermochemical data were obtained for the fluorine and chlorine oxides and some related hydrides, all of which are of interest for computational modeling of atmospheric processes. Our best available estimates for total atomization energies at 0 K are the following: HO2 165.97 +/- 0.14, H2O2 252.08 +/- 0.14, HOF 149.24 +/- 0.14, FO 51.17 +/- 0.10, F2O 89.43 +/- 0.14, FO2 130.15 +/- 0.16, F2O2 146.00 +/- 0.16, ClO 63.40 +/- 0.10, HOCl 156.73 +/- 0.14, Cl2O 96.93 +/- 0.16, OClO 122.33 +/- 0.16, ClOO 121.88 +/- 0.32, Cl2O2 142.9 +/- 0.3, ClO3 159.9 +/- 0.4, HClO2 192.0 +/- 0.4, HClO3 258.1 +/- 0.3, and HClO4 313.4 +/- 1 kcal/mol. For several of these species, the total atomization energy contains unusually large components from correlation effects beyond CCSD(T). The geometry of FOOF is significantly affected by connected quadruple excitations. A large variety of DFT exchange-correlation functionals have been evaluated for these systems and observations on their performance are offered. Our best available estimates for deltaHf,0o are the following: HO2 3.65 +/- 0.14, H2O2 -30.82 +/- 0.14, HOF -20.15 +/- 0.14, FO 26.28 +/- 0.11, F2O 6.48 +/- 0.14, FO2 6.30 +/- 0.16, F2O2 8.90 +/- 0.18, ClO 24.19 +/- 0.10, HOCl -17.51 +/- 0.14, Cl2O 19.24 +/- 0.16, OClO 24.26 +/- 0.16, ClOO 24.69 +/- 0.16, Cl2O2 32.3 +/- 0.3, ClO3 45.7 +/- 0.4, HClO2 6.2 +/- 0.4, HClO3 -0.9 +/- 0.3, and HClO4 2.9 +/- 1.0 kcal/mol. (The corresponding values at 298.15 K are 2.96 +/- 0.14, -32.24 +/- 0.14, -20.84 +/- 0.14, 26.43 +/- 0.11, 5.94 +/- 0.14, 5.87 +/- 0.16, 7.84 +/- 0.18, 24.18 +/- 0.10, -18.20 +/- 0.14, 18.82 +/- 0.16, 23.67 +/- 0.16, 24.30 +/- 0.16, 31.5 +/- 0.3, 44.3 +/- 0.4, 5.0 +/- 0.4, -2.6 +/- 0.3, and -0.1 +/- 1.0 kcal/mol, respectively.)
Bioinspired graphene membrane with temperature tunable channels for water gating and molecular separation
Publisher: Springer Science and Business Media LLC
Date: 08-12-2017
DOI: 10.1038/S41467-017-02198-5
Abstract: Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly( N -isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation.
Proton enhanced dynamic battery chemistry for aprotic lithium–oxygen batteries
Publisher: Springer Science and Business Media LLC
Date: 06-02-2017
DOI: 10.1038/NCOMMS14308
Abstract: Water contamination is generally considered to be detrimental to the performance of aprotic lithium–air batteries, whereas this view is challenged by recent contrasting observations. This has provoked a range of discussions on the role of water and its impact on batteries. In this work, a distinct battery chemistry that prevails in water-contaminated aprotic lithium–oxygen batteries is revealed. Both lithium ions and protons are found to be involved in the oxygen reduction and evolution reactions, and lithium hydroperoxide and lithium hydroxide are identified as predominant discharge products. The crystallographic and spectroscopic characteristics of lithium hydroperoxide monohydrate are scrutinized both experimentally and theoretically. Intriguingly, the reaction of lithium hydroperoxide with triiodide exhibits a faster kinetics, which enables a considerably lower overpotential during the charging process. The battery chemistry unveiled in this mechanistic study could provide important insights into the understanding of nominally aprotic lithium–oxygen batteries and help to tackle the critical issues confronted.
Accurate reaction barrier heights of pericyclic reactions: Surprisingly large deviations for the CBS-QB3 composite method and their consequences in DFT benchmark studies
Publisher: Wiley
Date: 03-02-2015
DOI: 10.1002/JCC.23837
Abstract: Accurate barrier heights are obtained for the 26 pericyclic reactions in the BHPERI dataset by means of the high-level Wn-F12 thermochemical protocols. Very often, the complete basis set (CBS)-type composite methods are used in similar situations, but herein it is shown that they in fact result in surprisingly large errors with root mean square deviations (RMSDs) of about 2.5 kcal mol(-1). In comparison, other composite methods, particularly G4-type and estimated coupled cluster with singles, doubles, and quasiperturbative triple excitations [CCSD(T)/CBS] approaches, show deviations well below the chemical-accuracy threshold of 1 kcal mol(-1). With the exception of SCS-MP2 and the herein newly introduced MP3.5 approach, all other tested Møller-Plesset perturbative procedures give poor performance with RMSDs of up to 8.0 kcal mol(-1). The finding that CBS-type methods fail for barrier heights of these reactions is unexpected and it is particularly troublesome given that they are often used to obtain reference values for benchmark studies. Significant differences are identified in the interpretation and final ranking of density functional theory (DFT) methods when using the original CBS-QB3 rather than the new Wn-F12 reference values for BHPERI. In particular, it is observed that the more accurate Wn-F12 benchmark results in lower statistical errors for those methods that are generally considered to be robust and accurate. Two ex les are the PW6B95-D3(BJ) hybrid-meta-general-gradient approximation and the PWPB95-D3(BJ) double-hybrid functionals, which result in the lowest RMSDs of the entire DFT study (1.3 and 1.0 kcal mol(-1), respectively). These results indicate that CBS-QB3 should be applied with caution in computational modeling and benchmark studies involving related systems.
Investigation of an Unusual Crystal Habit of Hydrochlorothiazide Reveals Large Polar Enantiopure Domains and a Possible Crystal Nucleation Mechanism
Publisher: Wiley
Date: 24-06-2019
A simple DFT-based diagnostic for nondynamical correlation
Publisher: Springer Science and Business Media LLC
Date: 05-12-2012
Quantum mechanical tunnelling
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CP01275D
Abstract: Quantum tunnelling can lower the effective barrier height, creating a discrepancy between experiment and theory.
Inorganic acid-catalyzed tautomerization of vinyl alcohol to acetaldehyde
Publisher: Elsevier BV
Date: 2014
MVO-10: A Gas-Phase Oxide Benchmark for Localization/Delocalization in Mixed-Valence Systems
Publisher: American Chemical Society (ACS)
Date: 06-06-2018
Abstract: Ten simple gas-phase, main-group as well as transition-metal, mixed-valence (MV) oxo complexes are suggested for the screening of electronic-structure methods for the computational study of localization vs delocalization of charge and spin density in MV systems, without the usual added complication of environmental effects. Benchmark coupled-cluster energies up to CCSDT(Q)/CBS (for Al
-, a Benchmark Gas-Phase Class II Mixed-Valence Radical Anion for the Evaluation of Quantum-Chemical Methods
Publisher: American Chemical Society (ACS)
Date: 29-07-2016
Abstract: The radical anion [Al2O4](-) has been identified as a rare ex le of a small gas-phase mixed-valence system with partially localized, weakly coupled class II character in the Robin/Day classification. It exhibits a low-lying C2v minimum with one terminal oxyl radical ligand and a high-lying D2h minimum at about 70 kJ/mol relative energy with predominantly bridge-localized-hole character. Two identical C2v minima and the D2h minimum are connected by two C2v-symmetrical transition states, which are only ca. 6-10 kJ/mol above the D2h local minimum. The small size of the system and the absence of environmental effects has for the first time enabled the computation of accurate ab initio benchmark energies, at the CCSDT(Q)/CBS level using W3-F12 theory, for a class-II mixed-valence system. These energies have been used to evaluate wave function-based methods [CCSD(T), CCSD, SCS-MP2, MP2, UHF] and density functionals ranging from semilocal (e.g., BLYP, PBE, M06L, M11L, N12) via global hybrids (B3LYP, PBE0, BLYP35, BMK, M06, M062X, M06HF, PW6B95) and range-separated hybrids (CAM-B3LYP, ωB97, ωB97X-D, LC-BLYP, LC-ωPBE, M11, N12SX), the B2PLYP double hybrid, and some local hybrid functionals. Global hybrids with about 35-43% exact-exchange (EXX) admixture (e.g., BLYP35, BMK), several range hybrids (CAM-B3LYP, ωB97X-D, ω-B97), and a local hybrid provide good to excellent agreement with benchmark energetics. In contrast, too low EXX admixture leads to an incorrect delocalized class III picture, while too large EXX overlocalizes and gives too large energy differences. These results provide support for previous method choices for mixed-valence systems in solution and for the treatment of oxyl defect sites in alumosilicates and SiO2. Vibrational gas-phase spectra at various computational levels have been compared directly to experiment and to CCSD(T)/aug-cc-pV(T+d)Z data.
Predicting the primary fragments in mass spectrometry using ab initio Roby–Gould bond indices
Publisher: Wiley
Date: 14-07-2018
DOI: 10.1002/QUA.25603
Accurate Heats of Formation for Polycyclic Aromatic Hydrocarbons: A High-Level Ab Initio Perspective
Publisher: American Chemical Society (ACS)
Date: 18-08-2021
Mechanistic insights into the autocatalyzed rearrangement of 2‐bromooxazolines to 2‐bromoisocyanates by means of high‐level quantum chemical methods
Publisher: Wiley
Date: 27-04-2021
DOI: 10.1002/POC.4214
Abstract: A mechanism for the thermal instability and selective rearrangement of 2‐bromooxazolines is proposed and examined using the highly accurate G4(MP2) thermochemical protocol. We propose this rearrangement to be autocatalyzed by bromide ions that are initially formed via a bimolecular reaction between two 2‐bromooxazoline molecules. We find this step to be rate determining, and it results in a consequent and more favorable propagative reaction of bromide ions with the starting material (2‐bromooxazoline). The proposed mechanism sheds light on experimental observations and provides a coherent explanation for 2‐bromooxazolines thermal instability. We proceed to rationalize the high barrier of the rate‐determining step via comparison with experimentally known pathways.
Fluxionality by quantum tunnelling
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CC04036G
Abstract: The 21-homododecahedryl cation is a unique system in terms of its fluxionality based on two different rearrangements. We report the quantum tunneling effects that drive the reactions at temperatures where the semi-classical kinetics are impossible.
Novel green phosphorene as a superior chemical gas sensing material
Publisher: Elsevier BV
Date: 2021
Benchmark Study of DFT Functionals for Late-Transition-Metal Reactions
Publisher: American Chemical Society (ACS)
Date: 29-10-2005
DOI: 10.1021/JP054449W
Abstract: The performance of a wide variety of DFT exchange-correlation functionals for a number of late-transition-metal reaction profiles has been considered. Benchmark ab-initio reference data for the prototype reactions Pd + H2, Pd + CH4, Pd + C2H6 (both C-C and C-H activation), and Pd + CH3Cl are presented, while ab-initio data of lesser quality were obtained for the catalytic hydrogenation of acetone and for the low-oxidation-state and high-oxidation-state mechanisms of the Heck reaction. "Kinetics" functionals such as mPW1K, PWB6K, BB1K, and BMK clearly perform more poorly for late-transition-metal reactions than for main-group reactions, as well as compared to general-purpose functionals. There is no single "best functional" for late-transition-metal reactions, but rather a cluster of several functionals (PBE0, B1B95, PW6B95, and TPSS25B95) that perform about equally well if main-group thermochemical performance is additionally considered, then B1B95 and PW6B95 emerge as the best performers. TPSS25B95 and TPSS33B95 offer attractive performance compromises if weak interactions and main-group barrier heights, respectively, are also important. In the ab-initio calculations, basis set superposition errors (BSSE) can be greatly reduced by ensuring that the metal spd shell has sufficient radial flexibility in the high-exponent range. Optimal HF percentages in hybrid functionals depend on the class of systems considered, increasing from anions to neutrals to cations to main-group barrier heights transition-metal barrier heights represent an intermediate situation. The use of meta-GGA correlation functionals appears to be quite beneficial.
Criegee intermediate decomposition pathways for the formation of o-toluic acid and 2-methylphenylformate
Publisher: Elsevier BV
Date: 06-2020
Effect of Substituents on the Preferred Modes of One-Electron Reductive Cleavage of N–Cl and N–Br Bonds
Publisher: American Chemical Society (ACS)
Date: 03-01-2013
DOI: 10.1021/JP310048F
Abstract: In this study, we investigate the effect of substituents in determining the modes of one-electron reductive cleavage of X-NRR' (X = Cl and Br) molecules. We achieve this through comparison of the calculated gas-phase electron affinities (EAs) and aqueous-phase one-electron reduction potentials (E°'s) for a range of nitrogen-centered radicals ((•)NRR') with the corresponding EA and E° values for (•)Cl and (•)Br. The gas-phase EAs have been obtained using the benchmark-quality W1w thermochemical protocol, whereas E° values have been obtained by additionally applying free energy of solvation corrections, obtained using the conductor-like polarizable continuum (CPCM) model. We find that the N-halogenated derivatives of amines and amides should generally cleave in such a way as to afford (•)NRR' and X(-). For the N-halogenated imides, on the other hand, the N-brominated derivatives are predicted to produce (•)Br in solution, whereas the N-chlorinated derivatives again would give Cl(-). Importantly, we predict that N-bromouracil is likely to afford (•)Br. This may have important implications in terms of inflammatory-related diseases, because (•)Br may damage biomolecules such as proteins and DNA. To assist in the determination of the gas-phase EAs of larger (•)NRR' radicals, not amenable to investigation using W1w, we have evaluated the performance of a wide range of lower-cost theoretical methods. Of the standard density functional theory (DFT) procedures, M06-2X, τ-HCTHh, and B3-LYP show good performance, with mean absolute deviations (MADs) from W1w of 4.8-6.8 kJ mol(-1), whereas ROB2-PLYP and B2-PLYP emerge as the best of the double-hybrid DFTs (DHDFTs), with MADs of 2.5 and 3.0 kJ mol(-1), respectively. Of the Gn-type procedures, G3X and G4 show very good performance (MADs = 2.4 and 2.6 kJ mol(-1), respectively). The G4(MP2)-6X+ procedure performs comparably, with an MAD of 2.7 kJ mol(-1), with the added advantage of significantly reduced computational expense.
Computational insights into the binding of pimodivir to the mutated PB2 subunit of the influenza A virus
Publisher: Informa UK Limited
Date: 14-05-2023
Heats of formation of platonic hydrocarbon cages by means of high‐level thermochemical procedures
Publisher: Wiley
Date: 12-06-2015
DOI: 10.1002/JCC.23963
Abstract: Hydrocarbon cages are key reference materials for the validation and parameterization of computationally cost-effective procedures such as density functional theory (DFT), semiempirical molecular orbital theory, and molecular mechanics. We obtain accurate total atomization energies (TAEs) and heats of formation (Δf H°298) for platonic and prismatic hydrocarbon cages by means of the Wn-F12 explicitly correlated thermochemical protocols. We consider the following kinetically stable (CH)n polycyclic hydrocarbon cages: (i) platonic hydrocarbons (tetrahedrane, cubane, and dodecahedrane), (ii) prismatic hydrocarbons (triprismane, cubane, and pentaprismane), and (iii) one truncated tetrahedrane (octahedrane). Our best theoretical heat of formation for cubane (144.8 kcal mol(-1)) suggests that the experimental value adopted by the NIST thermochemical database (142.7 ± 1.2 kcal mol(-1)) should be revised upwards by ∼2 kcal mol(-1). Our best heat of formation for dodecahedrane (20.2 kcal mol(-1)) suggests that the semiexperimental value (22.4 ± 1 kcal mol(-1)) should be revised downward by ∼2 kcal mol(-1). We use our benchmark Wn-F12 TAEs to evaluate the performance of a variety of computationally less demanding composite thermochemical procedures. These include the Gaussian-n (Gn) and the complete basis set (CBS) methods. The CBS-QB3 and CBS-APNO procedures show relatively poor performance with root-mean-squared deviations (RMSDs) of 4.2 and 2.5 kcal mol(-1), respectively. The best performers of the Gn procedures are G4 and G3(MP2)B3 (RMSD = 0.5 and 0.6 kcal mol(-1), respectively), while the worst performers are G3 and G4(MP2)-6X (RMSD = 2.1 and 2.9 kcal mol(-1), respectively). Isodesmic and even homodesmotic reactions involving these species are surprisingly challenging targets for DFT computations.
Post-CCSD(T) contributions to total atomization energies in multireference systems
Publisher: AIP Publishing
Date: 16-07-2018
DOI: 10.1063/1.5036795
Abstract: We examine the magnitude and the basis set convergence of post-coupled-cluster with single, double, and perturbative triple excitations (CCSD(T)) contributions (up to CCSDTQ567) for a wide and erse set of 21 first- and second-row molecules with up to four non-hydrogen atoms. We focus on multireference systems for which post-CCSD(T) effects are particularly pronounced. The considered molecules are BN(1∑+), C2(1∑+), O2, FO, P2, S2, ClO, N2O, NO2, O3, FNO, FO2, F2O, S2O, S3, ClNO, ClOO, Cl2O, N2C2, P4, and S4. This set spans the gamut from molecules dominated by moderate nondynamical correlation (e.g., FO, ClO, NO2, S2O, N2C2, and P4) to systems dominated by strong nondynamical correlation (e.g., BN, C2, FO2, O3, ClOO, and S4). We examine the basis set convergence of the CCSDT, CCSDT(Q), CCSDTQ, CCSDTQ(5), CCSDTQ5, CCSDTQ5(6), CCSDTQ56, CCSDTQ56(7), and CCSDTQ567 methods. The largest basis sets employed in each category are cc-pV6Z (CCSDT(Q)), cc-pV5Z (CCSDTQ), cc-pVTZ (CCSDTQ5(6)), and cc-pVDZ (CCSDTQ567). Apart from examining the basis-set convergence of post-CCSD(T) contributions near the one-particle basis-set limit, this work explores cost-effective approaches for obtaining these contributions from fairly small basis sets. We consider both effective basis-set extrapolations and scaling factors. An important finding is that extrapolating the perturbative connected quadruples, (Q), from the cc-pVDZ(4s3p1d) and cc-pVTZ basis sets yields near basis-set limit results and represents a significant improvement relative to cc-pV{D,T}Z extrapolation at no additional computational cost (where cc-pVDZ(4s3p1d) is an extended version of the cc-pVDZ basis set). Combining the (Q)/cc-pV{D(4s3p1d),T}Z extrapolations with the fully iterative connected quadruples, Q–(Q), contribution calculated with the cc-pVDZ (or even the cc-pVDZ(3s2p)) basis set is a cost-effective way for obtaining the connected quadruples component close to the basis-set limit (where cc-pVDZ(3s2p) is a truncated version of the cc-pVDZ basis set). In addition, we show that the (5)/cc-pVDZ(3s2p) and (6)/cc-pVDZ(3s2p) components provide reasonable approximations for the connected quintuple and sextuple components close to the basis-set limit, respectively.
Parapheromones for Thynnine Wasps
Publisher: Springer Science and Business Media LLC
Date: 14-12-2015
DOI: 10.1007/S10886-015-0660-0
Abstract: Sexually deceptive orchids produce floral volatiles that attract male insect pollinators. This interaction between flower and pollinator normally is highly specific. In the few cases where the chemical composition of the volatiles is known, the compounds have been found to be identical to those that comprise the sex pheromone of the female wasp. In this study, we investigated whether there is potential for flexibility in the molecular structure of the chemical cues used to mediate these specific interactions. Specifically, we asked whether strong sexual attraction can be maintained with structural modifications of sex pheromone components. Our study focused on the orchid, Drakaea glyptodon, which is pollinated by males of the thynnine wasp, Zaspilothynnus trilobatus. Three alkylpyrazines and a unique hydroxymethylpyrazine are components of the female produced sex pheromone of Z. trilobatus, and also the semiochemicals produced by the orchid that lures the males as pollinators. A blend of 2-butyl-3,5-dimethylpyrazine and 2-hydroxymethyl-3,5-diethyl-6-methylpyrazine (3:1) is as attractive as the full blend of four compounds. Therefore, in this study we substituted 2-hydroxymethyl-3,5-diethyl-6-methylpyrazine with one of five structurally related parapheromones in a blend with 2-butyl-3,5-dimethylpyrazine. All blends tested stimulated approaches by male wasps, with some also eliciting landing and attempted copulation. High-level calculations (G4(MP2)) showed the energy differences between the structural isomers were small, although the degree of sexual attraction varied, indicating the importance of structural factors for activity. One of the parapheromones, 2-hydroxymethyl-3,5-dimethyl-6-ethylpyrazine, elicited similar proportions of approaches, landings, and attempted copulations as the sex pheromone at the ratio and dose tested. The findings suggest that there is potential for chemical flexibility in the evolution of sexual deception.
Real-Time 2D NMR Identification of Analytes Undergoing Continuous Chromatographic Separation
Publisher: American Chemical Society (ACS)
Date: 08-01-2004
DOI: 10.1021/JA0389422
Abstract: We have recently proposed and demonstrated an approach that enables the acquisition of multidimensional nuclear magnetic resonance (NMR) spectra within a single scan. A promising application opened up by this new accelerated form of data acquisition concerns the possibility of monitoring in real time the chemical nature of analytes subject to a continuous flow. The present paper illustrates such potential, with the real-time acquisition of a series of 2D 1H NMR spectra arising from a mixture of compounds subject to a continuous liquid chromatography (LC) separation. This real-time 2D NMR identification of chemicals eluted minutes apart under usual LC-NMR conditions differs from the way in which LC-2D NMR has hitherto been carried out, which relies on stopped-flow modes of operations whereby fractions are first collected and then subject to in idual, aliquot-by-aliquot analyses. The real-time LC-2D NMR experiment hereby introduced can be implemented in a straightforward manner using modern commercial LC-NMR hardware, thus opening up immediate possibilities in high-throughput characterizations of complex molecules.
Co-Crystallization of Sym-Triiodo-Trifluorobenzene with Bipyridyl Donors: Consistent Formation of Two Instead of Anticipated Three N···I Halogen Bonds
Publisher: American Chemical Society (ACS)
Date: 18-01-2007
DOI: 10.1021/CG0607250
Theoretical Studies of Two Key Low-Lying Carbenes of C5H2Missing in the Laboratory
Publisher: American Chemical Society (ACS)
Date: 03-07-2019
Abstract: The equilibrium geometries and spectroscopic properties of two key singlet carbenes, buta-1,3-diynylcarbene (
A computational chemist's guide to accurate thermochemistry for organic molecules
Publisher: Wiley
Date: 15-02-2016
DOI: 10.1002/WCMS.1249
Explicitly correlated benchmark calculations on C8H8 isomer energy separations: how accurate are DFT, double-hybrid, and composite ab initio procedures?
Publisher: Informa UK Limited
Date: 02-07-2012
Thermochemistry of Guanine Tautomers Re-Examined by Means of High-Level CCSD(T) Composite Ab Initio Methods
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/CH19276
Abstract: We obtained accurate gas-phase tautomerization energies for a set of 14 guanine tautomers by means of high-level thermochemical procedures approximating the CCSD(T) energy at the complete basis set (CBS) limit. For the five low-lying tautomers, we use the computationally demanding W1-F12 composite method for obtaining the tautomerization energies. The relative W1-F12 tautomerization enthalpies at 298K are: 0.00 (1), 2.37 (2), 2.63 (3), 4.03 (3′), and 14.31 (4) kJmol−1. Thus, as many as four tautomers are found within a small energy window of less than 1.0kcalmol−1 (1kcalmol−1=4.184kJmol−1). We use these highly accurate W1-F12 tautomerization energies to evaluate the performance of a wide range of lower-level composite ab initio procedures. The Gn composite procedures (G4, G4(MP2), G4(MP2)-6X, G3, G3B3, G3(MP2), and G3(MP2)B3) predict that the enol tautomer (3) is more stable than the keto tautomer (2) by amounts ranging from 0.36 (G4) to 1.28 (G3(MP2)) kJmol−1. We also find that an approximated CCSD(T)/CBS energy calculated as HF/jul-cc-pV{D,T}Z+CCSD/jul-cc-pVTZ+(T)/jul-cc-pVDZ results in a root-mean-square deviation (RMSD) of merely 0.11kJmol−1 relative to the W1-F12 reference values. We use this approximated CCSD(T)/CBS method to obtain the tautomerization energies of 14 guanine tautomers. The relative tautomerization enthalpies at 298K are: 0.00 (1), 2.20 (2), 2.51 (3), 4.06 (3′), 14.30 (4), 25.65 (5), 43.78 (4′), 53.50 (6′), 61.58 (6), 77.37 (7), 82.52 (8′), 86.02 (9), 100.70 (10), and 121.01 (8) kJmol−1. Using these tautomerization enthalpies, we evaluate the performance of standard and composite methods for the entire set of 14 guanine tautomers. The best-performing procedures emerge as (RMSDs are given in parentheses): G4(MP2)-6X (0.51), CCSD(T)+ΔMP2/CBS (0.52), and G4(MP2) (0.64kJmol−1). The worst performers are CCSD(T)/AVDZ (1.05), CBS-QB3 (1.24), and CBS-APNO (1.38kJmol−1).
Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?
Publisher: AIP Publishing
Date: 06-2016
DOI: 10.1063/1.4952410
Abstract: In the context of high-accuracy computational thermochemistry, the valence coupled cluster with all singles and doubles (CCSD) correlation component of molecular atomization energies presents the most severe basis set convergence problem, followed by the (T) component. In the present paper, we make a detailed comparison, for an expanded version of the W4-11 thermochemistry benchmark, between, on the one hand, orbital-based CCSD/AV{5,6}Z + d and CCSD/ACV{5,6}Z extrapolation, and on the other hand CCSD-F12b calculations with cc-pVQZ-F12 and cc-pV5Z-F12 basis sets. This latter basis set, now available for H–He, B–Ne, and Al–Ar, is shown to be very close to the basis set limit. Apparent differences (which can reach 0.35 kcal/mol for systems like CCl4) between orbital-based and CCSD-F12b basis set limits disappear if basis sets with additional radial flexibility, such as ACV{5,6}Z, are used for the orbital calculation. Counterpoise calculations reveal that, while total atomization energies with V5Z-F12 basis sets are nearly free of BSSE, orbital calculations have significant BSSE even with AV(6 + d)Z basis sets, leading to non-negligible differences between raw and counterpoise-corrected extrapolated limits. This latter problem is greatly reduced by switching to ACV{5,6}Z core-valence basis sets, or simply adding an additional zeta to just the valence orbitals. Previous reports that all-electron approaches like HEAT (high-accuracy extrapolated ab-initio thermochemistry) lead to different CCSD(T) limits than “valence limit + CV correction” approaches like Feller-Peterson-Dixon and Weizmann-4 (W4) theory can be rationalized in terms of the greater radial flexibility of core-valence basis sets. For (T) corrections, conventional CCSD(T)/AV{Q,5}Z + d calculations are found to be superior to scaled or extrapolated CCSD(T)-F12b calculations of similar cost. For a W4-F12 protocol, we recommend obtaining the Hartree-Fock and valence CCSD components from CCSD-F12b/cc-pV{Q,5}Z-F12 calculations, but the (T) component from conventional CCSD(T)/aug’-cc-pV{Q,5}Z + d calculations using Schwenke’s extrapolation post-CCSD(T), core-valence, and relativistic corrections are to be obtained as in the original W4 theory. W4-F12 is found to agree slightly better than W4 with ATcT (active thermochemical tables) data, at a substantial saving in computation time and especially I/O overhead. A W4-F12 calculation on benzene is presented as a proof of concept.
Thermochemistry of phosphorus sulfide cages: an extreme challenge for high-level ab initio methods
Publisher: Springer Science and Business Media LLC
Date: 27-05-2019
Sol-Gel auto-combustion synthesis and physicochemical properties of BaAl2 O4 nanoparticles; electrochemical hydrogen storage performance and density functional theory
Publisher: Elsevier BV
Date: 12-2017
α-Hydrogen Abstraction by •OH and •SH Radicals from Amino Acids and Their Peptide Derivatives
Publisher: American Chemical Society (ACS)
Date: 07-03-2016
Abstract: We have used computational quantum chemistry to investigate the thermochemistry of α-hydrogen abstraction from the full set of amino acids normally found in proteins, as well as their peptide forms, by •OH and •SH radicals. These reactions, with their reasonable complexity in the electronic structure (at the α-carbon), are chosen as a consistent set of models for conducting a fairly robust assessment of theoretical procedures. Our benchmarking investigation shows that, in general, the performance for the various classes of theoretical methods improves in the order nonhybrid DFT → hybrid DFT → double-hybrid DFT → composite procedures. More specifically, we find that the DSD-PBE-P86 double-hybrid DFT procedure yields the best agreement with our high-level W1X-2 vibrationless barriers and reaction energies for this particular set of systems. A significant observation is that, when one considers relative instead of absolute values for the vibrationless barriers and reaction energies, even nonhybrid DFT procedures perform fairly well. To exploit this feature in a cost-effective manner, we have examined a number of multilayer schemes for the calculation of reaction energies and barriers for the abstraction reactions. We find that accurate values can be obtained when a "core" of glycine plus the abstracting radical is treated by DSD-PBE-P86, and the substituent effects are evaluated with M06-2X. Inspection of the set of calculated thermochemical data shows that the correlation between the free energy barriers and reaction free energies is strongest when the reactions are either endergonic or nearly thermoneutral.
Cope rearrangements in shapeshifting molecules re-examined by means of high-level CCSDT(Q) composite ab initio methods
Publisher: Elsevier BV
Date: 11-2020
Benchmark study of DFT and composite methods for bond dissociation energies in argon compounds
Publisher: Elsevier BV
Date: 03-2020
Thermochemical stabilities of giant fullerenes using density functional tight binding theory and isodesmic‐type reactions
Publisher: Wiley
Date: 20-11-2020
DOI: 10.1002/JCC.26449
Abstract: We present a systematic assessment of the density functional tight binding (DFTB) method for calculating heats of formation of fullerenes with isodesmic‐type reaction schemes. We show that DFTB3‐D/3ob can accurately predict Δ f H values of the 1812 structural isomers of C 60 , reproduce subtle trends in Δ f H values for 24 isolated pentagon rule (IPR) isomers of C 84 , and predict Δ f H values of giant fullerenes that are in effectively exact agreement with benchmark DSD‐PBEP86/def2‐QZVPP calculations. For fullerenes up to C 320 , DFTB Δ f H values are within 1.0 kJ mol −1 of DSD‐PBEP86/def2‐QZVPP values per carbon atom, and on a per carbon atom basis DFTB3‐D/3ob yields exactly the same numerical trend of (Δ f H [per carbon] = 722 n −0.72 + 5.2 kJ mol −1 ). DFTB3‐D/3ob is therefore an accurate replacement for high‐level DHDFT and composite thermochemical methods in predicting of thermochemical stabilities of giant fullerenes and analogous nanocarbon architectures.
Enhancement in hydrogen storage capacities of light metal functionalized Boron–Graphdiyne nanosheets
Publisher: Elsevier BV
Date: 06-2019
Drastic Improvement in Gas-Sensing Characteristics of Phosphorene Nanosheets under Vacancy Defects and Elemental Functionalization
Publisher: American Chemical Society (ACS)
Date: 14-08-2018
Platinum Stilbazoles: Ring-Walking Coupled with Aryl−Halide Bond Activation
Publisher: American Chemical Society (ACS)
Date: 10-06-2005
DOI: 10.1021/JA050613H
Abstract: The reaction between tetrakis(triethylphosphine)platinum(0) and 4-[trans-2-(4-bromophenyl)vinyl]pyridine (1) is examined. Initially, the metal center coordinates to the bridging double bond of 1. Complexes 2 and 3 were fully characterized, and their X-ray crystallography structures are presented. Upon heating, either in solution or in the solid state, complex 2 undergoes C-Br oxidative addition to give complex 3. Kinetic studies revealed that this conversion is unimolecular and does not involve dissociation of the metal center from the double bond. Density functional studies show that a plausible mechanism involves the metal center "walking" around the pi-system from the bridging C=C double bond to the C-Br bond.
The High Performance of Choline Arginate for Biomass Pretreatment Is Due to Remarkably Strong Hydrogen Bonding by the Anion
Publisher: American Chemical Society (ACS)
Date: 25-08-2018
Performance of Ab Initio and Density Functional Methods for Conformational Equilibria of CnH2n+2 Alkane Isomers (n = 4−8)
Publisher: American Chemical Society (ACS)
Date: 10-2009
DOI: 10.1021/JP903640H
Abstract: Conformational energies of n-butane, n-pentane, and n-hexane have been calculated at the CCSD(T) level and at or near the basis set limit. Post-CCSD(T) contributions were considered and found to be unimportant. The data thus obtained were used to assess the performance of a variety of density functional methods. Double-hybrid functionals like B2GP-PLYP and B2K-PLYP, especially with a small Grimme-type empirical dispersion correction, are capable of rendering conformational energies of CCSD(T) quality. These were used as a "secondary standard" for a larger s le of alkanes, including isopentane and the branched hexanes as well as key isomers of heptane and octane. Popular DFT functionals like B3LYP, B3PW91, BLYP, PBE, and PBE0 tend to overestimate conformer energies without dispersion correction, while the M06 family severely underestimates GG interaction energies. Grimme-type dispersion corrections for these overcorrect and lead to qualitatively wrong conformer orderings. All of these functionals also exhibit deficiencies in the conformer geometries, particularly the backbone torsion angles. The PW6B95 and, to a lesser extent, BMK functionals are relatively free of these deficiencies. Performance of these methods is further investigated to derive conformer ensemble corrections to the enthalpy function, H(298) - H(0), and the Gibbs energy function, gef(T) identical with -[G(T) - H(0)]/T, of these alkanes. These are essential for accurate computed heats of formation of especially the larger species as the corrections for these are several times the expected uncertainty in modern computational thermochemistry methods such as W4 theory. While H(298) - H(0) is only moderately sensitive to the level of theory, gef(T) exhibits more pronounced sensitivity. Once again, double hybrids acquit themselves very well. The effects of zero-point energy and nonfactorizable rovibrational partition functions have been considered.
The duhka of DFT
Publisher: CSIRO Publishing
Date: 28-03-2022
DOI: 10.1071/CH21332
Abstract: Density functional theory (DFT) is currently experiencing a golden age. The past two decades witnessed remarkable advances in the general applicability of density functionals in the top rungs of Jacob’s Ladder. Nevertheless, Jacob’s Ladder may have reached its highest rung in terms of dependencies on occupied (rung four) and unoccupied orbitals (rung five). Moreover, the fifth rung is associated with a computational cost far greater than the lower rungs. Another limitation is that each rung includes dozens of different functionals, and at present, there is no clear pathway for systematic improvements within each rung of the ladder. This highlight provides an overview of the exchange–correlation (XC) hole and how it could be used in developing new density functionals. We begin with a brief overview of the current status and challenges in developing better density functionals, followed by the intimate relationship between the XC functional and hole. We present a conceptually simple and computationally economical method for calculating the XC hole and how this method could offer new directions in developing better exchange–correlation functionals.
Shapeshifting radicals
Publisher: Elsevier BV
Date: 2022
Theoretical Studies of SiC4H2 Isomers Delineate Three Low-Lying Silylidenes Are Missing in the Laboratory
Publisher: American Chemical Society (ACS)
Date: 06-01-2020
Abstract: Eleven isomers of SiC
High-level thermochemistry for the octasulfur ring: A converged coupled cluster perspective for a challenging second-row system
Publisher: Elsevier BV
Date: 12-2021
Reaction barrier heights for cycloreversion of heterocyclic rings: An Achilles’ heel for DFT and standard ab initio procedures
Publisher: Elsevier BV
Date: 09-2015
A Computational Foray into the Mechanism and Catalysis of the Adduct Formation Reaction of Guanine with Crotonaldehyde
Publisher: Wiley
Date: 09-10-2019
DOI: 10.1002/JCC.25595
Abstract: Crotonaldehyde, a common environmental pollutant and product of endogenous lipid peroxidation, reacts with guanine to form DNA adducts with pronounced genotoxicity and mutagenicity. Here, we explore the molecular mechanism of this adduct formation using double-hybrid density functional theory methods. The reaction can be envisaged to occur in a two-step fashion via an aza-Michael addition leading to an intermediate ring-open adduct followed by a cyclization reaction giving the mutagenic ring-closed adduct. We find that (i) a 1,2-type addition is favored over a 1,4-type addition for the aza-Michael addition, and (ii) an initial tautomerization of the guanine moiety in the resulting ring-open adduct significantly reduces the barrier toward cyclization compared to the direct cyclization of the ring-open adduct in its keto-form. Overall, the aza-Michael addition is found to be rate-determining. We further find that participation of a catalytic water molecule significantly reduces the energy barriers of both the addition and cyclization reaction. © 2018 Wiley Periodicals, Inc.
Computational insights for the hydride transfer and distinctive roles of key residues in cholesterol oxidase
Publisher: Springer Science and Business Media LLC
Date: 08-12-2017
DOI: 10.1038/S41598-017-17503-X
Abstract: Cholesterol oxidase (ChOx), a member of the glucose-methanol-choline (GMC) family, catalyzes the oxidation of the substrate via a hydride transfer mechanism and concomitant reduction of the FAD cofactor. Unlike other GMC enzymes, the conserved His447 is not the catalytic base that deprotonates the substrate in ChOx. Our QM/MM MD simulations indicate that the Glu361 residue acts as a catalytic base facilitating the hydride transfer from the substrate to the cofactor. We find that two rationally chosen point mutations (His447Gln and His447Asn) cause notable decreases in the catalytic activity. The binding free energy calculations show that the Glu361 and His447 residues are important in substrate binding. We also performed high-level double-hybrid density functional theory simulations using small model systems, which support the QM/MM MD results. Our work provides a basis for unraveling the substrate oxidation mechanism in GMC enzymes in which the conserved histidine does not act as a base.
A dataset of highly accurate homolytic NBr bond dissociation energies obtained by Means of W2 theory
Publisher: Wiley
Date: 13-10-2016
DOI: 10.1002/QUA.25024
Catalysis on Pristine 2D Materials via Dispersion and Electrostatic Interactions
Publisher: American Chemical Society (ACS)
Date: 29-07-2020
Economical Post-CCSD(T) Computational Thermochemistry Protocol and Applications to Some Aromatic Compounds
Publisher: American Chemical Society (ACS)
Date: 05-03-2009
DOI: 10.1021/JP900056W
Abstract: To achieve a kilojoules-per-mole level of accuracy consistently in computational thermochemistry, the inclusion of post-CCSD(T) correlation effects cannot be avoided. Such effects are included in the W4 and HEAT computational thermochemistry protocols. The principal bottleneck in carrying out such calculations for larger systems is the evaluation of the T(3)-(T) term. We propose a cost-effective empirical approximation for this term that does not entail any reliance on experimental data. For first-row molecules, our W3.2lite protocol yields atomization energies with a 95% confidence interval of approximately 0.4 kcal/mol at the expense of introducing two such parameters. W3.2lite has been successfully applied to aromatic and aliphatic hydrocarbons such as benzene, fulvene, phenyl radical, pyridine, furan, benzyne isomers, trans-butadiene, cyclobutene, [1.1.1]propellane, and bicyclo[1.1.1]pentane. The W3.2lite predictions for fulvene, phenyl radical, cyclobutene, and [1.1.1]propellane are impossible to reconcile with experiment and suggest that remeasurement may be in order.
Estimating the CCSD basis-set limit energy from small basis sets: basis-set extrapolations vs additivity schemes
Publisher: AIP Publishing
Date: 05-2015
DOI: 10.1063/1.4921697
Abstract: Coupled cluster calculations with all single and double excitations (CCSD) converge exceedingly slowly with the size of the one-particle basis set. We assess the performance of a number of approaches for obtaining CCSD correlation energies close to the complete basis-set limit in conjunction with relatively small DZ and TZ basis sets. These include global and system-dependent extrapolations based on the A + B/Lα two-point extrapolation formula, and the well-known additivity approach that uses an MP2-based basis-set-correction term. We show that the basis set convergence rate can change dramatically between different systems(e.g.it is slower for molecules with polar bonds and/or second-row elements). The system-dependent basis-set extrapolation scheme, in which unique basis-set extrapolation exponents for each system are obtained from lower-cost MP2 calculations, significantly accelerates the basis-set convergence relative to the global extrapolations. Nevertheless, we find that the simple MP2-based basis-set additivity scheme outperforms the extrapolation approaches. For ex le, the following root-mean-squared deviations are obtained for the 140 basis-set limit CCSD atomization energies in the W4-11 database: 9.1 (global extrapolation), 3.7 (system-dependent extrapolation), and 2.4 (additivity scheme) kJ mol–1. The CCSD energy in these approximations is obtained from basis sets of up to TZ quality and the latter two approaches require additional MP2 calculations with basis sets of up to QZ quality. We also assess the performance of the basis-set extrapolations and additivity schemes for a set of 20 basis-set limit CCSD atomization energies of larger molecules including amino acids, DNA/RNA bases, aromatic compounds, and platonic hydrocarbon cages. We obtain the following RMSDs for the above methods: 10.2 (global extrapolation), 5.7 (system-dependent extrapolation), and 2.9 (additivity scheme) kJ mol–1.
A Self-Replicating Linear DNA
Publisher: American Chemical Society (ACS)
Date: 20-03-2020
Computational design of bio-inspired carnosine-based HOBr antioxidants
Publisher: Springer Science and Business Media LLC
Date: 08-09-2017
DOI: 10.1007/S10822-017-0060-3
Abstract: During a respiratory burst the enzyme myeloperoxidase generates significant amounts of hypohalous acids (HOX, X = Cl and Br) in order to inflict oxidative damage upon invading pathogens. However, excessive production of these potent oxidants is associated with numerous inflammatory diseases. It has been suggested that the endogenous antioxidant carnosine is an effective HOCl scavenger. Recent computational and experimental studies suggested that an intramolecular Cl
Restricted-Open-Shell G4(MP2)-Type Procedures
Publisher: American Chemical Society (ACS)
Date: 11-11-2016
Abstract: In the present study, we have reformulated the G4(MP2) and G4(MP2)-6X procedures for use with a restricted-open-shell (RO) formalism. We find that the resulting ROG4(MP2) and ROG4(MP2)-6X procedures generally perform comparably to the original unrestricted (U) variants, including their performance on radicals. Our analysis suggests that this is due mainly to the inclusion of empirical parameters that overcome the slightly less good performance of the U variants. However, a major practical advantage of ROG4(MP2) and ROG4(MP2)-6X is that they can be used in a wider range of computational chemistry software packages than the U analogs. We have demonstrated the importance of this aspect with a large-scale ROG4(MP2)-6X computation for the dissociation of the dodecahedryl dimer (C
Double-Hybrid Functionals for Thermochemical Kinetics
Publisher: American Chemical Society (ACS)
Date: 15-12-2007
DOI: 10.1021/JP710179R
Abstract: We propose two new double-hybrid functionals, denoted B2K-PLYP and mPW2K-PLYP, which yield thermochemical performance comparable to existing double-hybrid functionals but offer superior performance for barrier heights of various kinds. We show that the new functionals yield excellent performance for all of the following: (a) main-group thermochemistry (b) main-group thermochemical kinetics (c) late transition metal reactions. In addition, B2K-PLYP performs well for weak interactions.
PAH335 – A diverse database of highly accurate CCSD(T) isomerization energies of 335 polycyclic aromatic hydrocarbons
Publisher: Elsevier BV
Date: 08-2023
Evaluation of density functional theory for a large and diverse set of organic and inorganic equilibrium structures
Publisher: Wiley
Date: 13-06-2021
DOI: 10.1002/JCC.26698
Abstract: Density functional theory (DFT) has been extensively benchmarked for energetic properties however, less attention has been given to equilibrium structures and the effect of using a certain DFT geometry on subsequent energetic properties. We evaluate the performance of 52 contemporary DFT methods for obtaining the structures of 122 species in the W4‐11‐GEOM database. This dataset includes a total of 246 unique bonds: 117 H─X, 65 X─Y, 49 X═Y, and 15 XY bonds (where X and Y are first‐ and second‐row atoms) and 133 key bond angles: 96 X‐Y‐H, 22 X‐Y‐Z, and 15 H‐X‐H angles. The reference geometries are optimized at the CCSD(T)/jul‐cc‐pV( n +d)Z level of theory ( n = 5, 6). The performance of DFT is evaluated in conjunction with the Def2‐ n ZVPP ( n = T, Q), cc‐pV(T+d)Z, and jul‐cc‐pV(T+d)Z basis sets. The root‐mean‐square deviations (RMSDs) over the bond distances of the best performing functionals from each rung of Jacob's Ladder are 0.0086 (SOGGA11), 0.0088 (τ‐HCTH), 0.0059 (B3LYP), 0.0054 (TPSSh), and 0.0032 (DSD‐PBEP86) Å. We evaluate the effect of the choice of the DFT geometry on subsequent molecular energies calculated with W1‐F12 theory. Geometries obtained with GGA and MGGA methods result in large RMSDs in the subsequent W1‐F12 energies however, six hybrid GGA functionals (B3LYP, B3P86, mPW3PBE, B3PW91, mPW1LYP, and X3LYP) result in an excellent performance with RMSDs between 0.25 and 0.30 kJ mol −1 relative to the CCSD(T)/CBS reference geometries. The B2GP‐PLYP and mPW2‐PLYP DHDFT methods result in near‐CCSD(T) accuracy with RMSDs of 0.11 and 0.10 kJ mol −1 , respectively.
Atomistic simulations of the aggregation of small aromatic molecules in homogenous and heterogenous mixtures
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP02622K
Abstract: We describe a mechanism and structural analysis for cosmic dust grain seed formation around carbon-rich stars via polyaromatic hydrocarbon aggregation using computer simulations.
Heterologous biosynthesis of elsinochrome A sheds light on the formation of the photosensitive perylenequinone system
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8SC02870B
Abstract: Formation of the three C–C bridges between the two naphthol monomers for elsinochrome ( 1 ) involves three distinct classes of oxidases.
Polycyclic aromatic hydrocarbons: from small molecules through nano-sized species towards bulk graphene
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CP01659H
Abstract: Accurate energetics of polycyclic aromatic hydrocarbons from isodesmic-type reactions show that nano-graphene converges to bulk graphene at ∼10 nm.
Mechanistic Insights into Water-Catalyzed Formation of Levoglucosenone from Anhydrosugar Intermediates by Means of High-Level Theoretical Procedures
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/CH16206
Abstract: Levoglucosenone (LGO) is an important anhydrosugar product of fast pyrolysis of cellulose and biomass. We use the high-level G4(MP2) thermochemical protocol to study the reaction mechanism for the formation of LGO from the 1,4:3,6-dianhydro-α-d-glucopyranose (DGP) pyrolysis intermediate. We find that the DGP-to-LGO conversion proceeds via a multistep reaction mechanism, which involves ring-opening, ring-closing, enol-to-keto tautomerization, hydration, and dehydration reactions. The rate-determining step for the uncatalyzed process is the enol-to-keto tautomerization (ΔG‡298 = 68.6 kcal mol–1). We find that a water molecule can catalyze five of the seven steps in the reaction pathway. In the water-catalyzed process, the barrier for the enol-to-keto tautomerization is reduced by as much as 15.1 kcal mol–1, and the hydration step becomes the rate-determining step with an activation energy of ΔG‡298 = 58.1 kcal mol–1.
Kinetics and Thermodynamics of Reactions Involving Criegee Intermediates: An Assessment of Density Functional Theory and Ab Initio Methods Through Comparison with CCSDT(Q)/CBS Data
Publisher: Wiley
Date: 21-11-2020
DOI: 10.1002/JCC.26106
Abstract: Reactions involving Criegee intermediates (CIs, R
Relative energies of increasingly large [ n ]helicenes by means of high-level quantum chemical methods
Publisher: Informa UK Limited
Date: 02-08-2023
Catalytic effect of graphene on the inversion of corannulene using a continuum approach with the Lennard-Jones potential
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3NA00349C
Abstract: The catalytic effect of graphene on the corannulene bowl-to-bowl inversion is confirmed in this paper using a pair-wise dispersion interaction model.
Selective sp3 C-H activation of ketones at the β position by Ir(I). Origin of regioselectivity and water effect
Publisher: American Chemical Society (ACS)
Date: 31-08-2006
DOI: 10.1021/JA0641352
Intramolecular Proton-Coupled Hydride Transfers with Relatively Low Activation Barriers
Publisher: American Chemical Society (ACS)
Date: 27-06-2023
Prototypical π–π dimers re-examined by means of high-level CCSDT(Q) composite ab initio methods
Publisher: AIP Publishing
Date: 25-03-2021
DOI: 10.1063/5.0043046
Abstract: The benzene–ethene and parallel-displaced (PD) benzene–benzene dimers are the most fundamental systems involving π–π stacking interactions. Several high-level ab initio investigations calculated the binding energies of these dimers using the coupled-cluster with singles, doubles, and quasi-perturbative triple excitations [CCSD(T)] method at the complete basis set [CBS] limit using various approaches such as reduced virtual orbital spaces and/or MP2-based basis set corrections. Here, we obtain CCSDT(Q) binding energies using a Weizmann-3-type approach. In particular, we extrapolate the self-consistent field (SCF), CCSD, and (T) components using large heavy-atom augmented Gaussian basis sets [namely, SCF/jul-cc-pV{5,6}Z, CCSD/jul-cc-pV{Q,5}Z, and (T)/jul-cc-pV{T,Q}Z]. We consider post-CCSD(T) contributions up to CCSDT(Q), inner-shell, scalar-relativistic, and Born–Oppenheimer corrections. Overall, our best relativistic, all-electron CCSDT(Q) binding energies are ∆Ee,all,rel = 1.234 (benzene–ethene) and 2.550 (benzene–benzene PD), ∆H0 = 0.949 (benzene–ethene) and 2.310 (benzene–benzene PD), and ∆H298 = 0.130 (benzene–ethene) and 1.461 (benzene–benzene PD) kcal mol−1. Important conclusions are reached regarding the basis set convergence of the SCF, CCSD, (T), and post-CCSD(T) components. Explicitly correlated calculations are used as a sanity check on the conventional binding energies. Overall, post-CCSD(T) contributions are destabilizing by 0.028 (benzene–ethene) and 0.058 (benzene–benzene) kcal mol−1, and thus, they cannot be neglected if sub-chemical accuracy is sought (i.e., errors below 0.1 kcal mol−1). CCSD(T)/aug-cc-pwCVTZ core–valence corrections increase the binding energies by 0.018 (benzene–ethene) and 0.027 (benzene–benzene PD) kcal mol−1. Scalar-relativistic and diagonal Born–Oppenheimer corrections are negligibly small. We use our best CCSDT(Q) binding energies to evaluate the performance of MP2-based, CCSD-based, and lower-cost composite ab initio procedures for obtaining these challenging π–π stacking binding energies.
From High-Energy C7H2 Isomers with A Planar Tetracoordinate Carbon Atom to An Experimentally Known Carbene
Publisher: American Chemical Society (ACS)
Date: 26-10-2018
Abstract: In this work, we use high-level ab initio procedures to show that the high-energy isomers of C
Evaluation of the performance of MP4-based procedures for a wide range of thermochemical and kinetic properties
Publisher: Elsevier BV
Date: 11-2016
Improved Adsorption and Migration of Divalent Ions Over C4N Nanosheets: Potential Anode for Divalent Batteries
Publisher: Elsevier BV
Date: 12-2020
6‐Endo‐dig versus 5‐exo‐dig: Exploring Radical Cyclization Preference with First‐, Second‐, and Third‐row Linkers using High‐level Quantum Chemical Methods
Publisher: Wiley
Date: 18-07-2023
Abstract: As an expansion upon Baldwin rules, the cyclization reactions of hex‐5‐yn‐1‐yl radical systems with different first‐, second‐, and third‐row linkers are explored at the CCSD(T) level via means of the SMD(benzene)‐G4(MP2) thermochemical protocol. Unlike C, O, and N linkers, systems with B, Si, P, S, Ge, As, and Se linkers are shown to favor 6‐endo‐dig cyclization. This offers fundamental insights into the rational synthetic design of cyclic compounds. A thorough analysis of stereoelectronic effects, cyclization barriers, and intrinsic barriers illustrates that structural changes alter the cyclization preference by mainly impacting 5‐exo‐dig reaction barriers. Based on the high‐level computational modeling, we proceed to develop a new tool for cyclization preference prediction from the correlation between cyclization barriers and radical structural parameters (e. g., linker bond length and bond angle). A strong correlation is found between the radical attack trajectory angle and the reaction barrier heights, i. e., cyclization preference. Finally, the influence of stereoelectronic effects on the two radical cyclization pathways is further investigated in stereoisomers of hypervalent silicon system, which provides novel insight into cyclization control.
Computational investigation into the gas-phase ozonolysis of the conjugated monoterpene a-phellandrene
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP04695A
Abstract: The gas-phase ozonolysis mechanism of α-phellandrene is studied for the first time using high-level computational methods.
Directing Aryl−I versus Aryl−Br Bond Activation by Nickel via a Ring Walking Process
Publisher: American Chemical Society (ACS)
Date: 17-05-2008
DOI: 10.1021/IC702289N
Abstract: Activation of a strong aryl-Br bond of a halogenated vinylarene by nickel(0) is demonstrated in the presence of aryl-I containing substrates. eta2-Coordination of Ni(PEt3)2 to the C=C moiety of halogenated vinylarenes is kinetically preferable and is followed by an intramolecular aryl-halide bond activation process. This "ring-walking" process is quantitative and proceeds under mild reaction conditions in solution. Mechanistic studies indicate that the metal insertion into the aryl-halide bond is not the rate-determining step. The reaction obeys first-order kinetics in the eta2-coordination complexes with almost identical activation parameters for Br and I derivatives. The ring-walking process is kinetically accessible as shown by density functional theory (DFT) calculations at the PBE0/SDB-cc-pVDZ//PBE0/SDD level of theory.
Bond orders for intermolecular interactions in crystals: charge transfer, ionicity and the effect on intramolecular bonds
Publisher: International Union of Crystallography (IUCr)
Date: 29-08-2018
DOI: 10.1107/S2052252518010758
Abstract: The question of whether intermolecular interactions in crystals originate from localized atom...atom interactions or as a result of holistic molecule...molecule close packing is a matter of continuing debate. In this context, the newly introduced Roby–Gould bond indices are reported for intermolecular `σ-hole' interactions, such as halogen bonding and chalcogen bonding, and compared with those for hydrogen bonds. A series of 97 crystal systems exhibiting these interaction motifs obtained from the Cambridge Structural Database (CSD) has been analysed. In contrast with conventional bond-order estimations, the new method separately estimates the ionic and covalent bond indices for atom...atom and molecule...molecule bond orders, which shed light on the nature of these interactions. A consistent trend in charge transfer from halogen/chalcogen bond-acceptor to bond-donor groups has been found in these intermolecular interaction regions via Hirshfeld atomic partitioning of the electron populations. These results, along with the `conservation of bond orders' tested in the interaction regions, establish the significant role of localized atom...atom interactions in the formation of these intermolecular binding motifs.
Related Organisations
Related Funding Activities
An STM/AFM Facility For Electroactive Materials Characterisation
Start Date: 2015
End Date: 2015
Funder: Australian Research Council
View Funded ActivityQuantum Chemical Methods: From Wavefunction To Density Functional Theory
Start Date: 2017
End Date: 2020
Funder: Australian Research Council
View Funded ActivityARC Future Fellowships - Grant ID: FT170100373
Start Date: 12-2017
End Date: 02-2022
Amount: $880,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Early Career Researcher Award - Grant ID: DE140100311
Start Date: 2014
End Date: 05-2017
Amount: $395,220.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP200101664
Start Date: 03-2021
End Date: 02-2024
Amount: $461,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE150100148
Start Date: 2015
End Date: 12-2016
Amount: $150,916.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP110102336
Start Date: 01-2011
End Date: 12-2013
Amount: $245,538.00
Funder: Australian Research Council
View Funded Activity