Journal ArticleDOI
Assessment of Density Functional Theory for Model SN2 Reactions: CH3X + F- (X = F, Cl, CN, OH, SH, NH2, PH2)
TLDR
In this paper, the B3LYP, BLYP, and BP86 variants of density functional theory, in conjunction with double and triple ζ basis sets, have been examined for SN2 reactions of the type CH3X + F- → CH3F + X- (X = F, C...Abstract:
The B3LYP, BLYP, and BP86 variants of density functional theory, in conjunction with double and triple ζ basis sets, have been examined for SN2 reactions of the type CH3X + F- → CH3F + X- (X = F, C...read more
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Benchmark Database of Barrier Heights for Heavy Atom Transfer, Nucleophilic Substitution, Association, and Unimolecular Reactions and Its Use to Test Theoretical Methods
TL;DR: A benchmark database of forward and reverse barrier heights for 19 non-hydrogen-transfer reactions has been developed by using Weizmann 1 calculations, and 29 DFT methods and 6 ab initio wave function theory (WFT) methods have been tested against the new database as well as against an older database for hydrogen atom transfer reactions.
Journal ArticleDOI
Performance of the OPBE exchange-correlation functional
TL;DR: In a recent evaluation of density functional theory (DFT) functionals OPBE, which combines Handy's optimized exchange (OPTX) with the PBE correlation, was shown to correctly predict the spin states (singlet through sextet) of seven different iron complexes as mentioned in this paper.
Journal ArticleDOI
A SN2 Reaction That Avoids Its Deep Potential Energy Minimum
TL;DR: The finding that the majority of trajectories avoided this potential energy minimum and instead dissociated directly to products and may be applicable to other reactive systems where there is a hierarchy of time scales for intramolecular motions and thus inefficient IVR.
Journal ArticleDOI
Farewell to the HSAB Treatment of Ambident Reactivity
TL;DR: It is demonstrated that the HSAB as well as the related Klopman-Salem model do not even correctly predict the behavior of the prototypes of ambident nucleophiles and, therefore, are rather misleading instead of useful guides.
Journal ArticleDOI
Interfacing Q‐Chem and CHARMM to perform QM/MM reaction path calculations
H. Lee Woodcock,Milan Hodošček,Andrew T. B. Gilbert,Peter Gill,Henry F. Schaefer,Bernard R. Brooks +5 more
TL;DR: A hybrid quantum mechanical/molecular mechanical (QM/MM) potential energy function with Hartree‐Fock, density functional theory (DFT), and post‐HF (RIMP2, MP2, CCSD) capability has been implemented in the CHARMM and Q‐Chem software packages.
References
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Journal ArticleDOI
Density‐functional thermochemistry. III. The role of exact exchange
TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
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Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
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Density-functional exchange-energy approximation with correct asymptotic behavior.
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
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Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen
TL;DR: In this paper, a detailed study of correlation effects in the oxygen atom was conducted, and it was shown that primitive basis sets of primitive Gaussian functions effectively and efficiently describe correlation effects.
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The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors
TL;DR: In this paper, a direct difference method for the computation of molecular interactions has been based on a bivariational transcorrelated treatment, together with special methods for the balancing of other errors.