title: 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.
abstract: Rate constants and (12)C/(13)C kinetic isotope effects are calculated by direct dynamics for the OH + CH(4) --> H(2)O + CH(3) 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 (12)C/(13)C 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.
authors.affiliation: Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455-0431, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Ellingson
authors.forename: Jingzhi
authors.initials: J
authors.lastname: Pu
authors.forename: Hai
authors.initials: H
authors.lastname: Lin
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Donald G
authors.initials: DG
authors.lastname: Truhlar
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D008697:Methane / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D017665:Hydroxyl Radical; D008697:Methane