Multicoefficient Gaussian-3 Calculation of the Rate Constant for the OH + CH4 Reaction and Its 12C/13C Kinetic Isotope Effect with Emphasis on the Effects of Coordinate System and Torsional Treatment

Rate constants and 12C/13C kinetic isotope effects are calculated by direct dynamics for the OH + CH4 → H2O + CH3 reaction. The electronic structure calculations required to generate the implicit potential energy surface were carried out by the high-level multicoefficient Gaussian-3/version-3 (MCG3)...

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Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2007-11, Vol.111 (45), p.11706-11717
Main Authors: Ellingson, Benjamin A, Pu, Jingzhi, Lin, Hai, Zhao, Yan, Truhlar, Donald G
Format: Article
Language:English
Subjects:
Carbon Isotopes - chemistry
Hydroxyl Radical - chemistry
Kinetics
Methane - chemistry
Online Access:Get full text
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Summary:Rate constants and 12C/13C kinetic isotope effects are calculated by direct dynamics for the OH + CH4 → H2O + CH3 reaction. The electronic structure calculations required to generate the implicit potential energy surface were carried out by the high-level multicoefficient Gaussian-3/version-3 (MCG3) method and compared to two other multilevel methods, MC3BB and MC3MPW, and three density functional methods, M06-2X, BB1K, and MPW1K. The rate constants and 12C/13C kinetic isotope effects are shown to depend strongly on the coordinate system used to calculate the frequencies as well as on the method used to account for the torsional anharmonicity of the lowest-frequency vibrational mode of the generalized transition states.
ISSN:1089-5639
1520-5215
DOI:10.1021/jp072843j