Temperature Dependence of Carbon-13 Kinetic Isotope Effects of Importance to Global Climate Change
- 11 February 2005
- journal article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 127 (9), 2830-2831
- https://doi.org/10.1021/ja0434026
Abstract
We report here a theoretical study of the 13C kinetic isotope effect (KIE) and its temperature dependence for the reaction OH + CH4 → H2O + CH3, the major sink of atmospheric methane in the troposphere. The KIE values at various atmospherically significant temperatures were determined by direct dynamics using variational transition state theory with multidimensional tunneling contributions (VTST/MT). The potential energy surfaces (PESs) were generated by hybrid density functional theory as well as by recently developed doubly hybrid density functional theory methods. Comparisons of our calculated KIEs with experimental data and theoretical values in the literature reveal the critical contributions due to multidimensional tunneling and torsion anharmonicity as well as the critical issue of the choice of internal rotational axis.Keywords
This publication has 17 references indexed in Scilit:
- Carbon and hydrogen isotopic compositions of stratospheric methane: 2. Two‐dimensional model results and implications for kinetic isotope effectsJournal of Geophysical Research: Atmospheres, 2003
- Effectiveness of Diffuse Basis Functions for Calculating Relative Energies by Density Functional TheoryThe Journal of Physical Chemistry A, 2003
- Carbon 13 and D kinetic isotope effects in the reactions of CH4 with O(1D) and OH: New laboratory measurements and their implications for the isotopic composition of stratospheric methaneJournal of Geophysical Research: Atmospheres, 2001
- Molecular Mechanics for Chemical Reactions: A Standard Strategy for Using Multiconfiguration Molecular Mechanics for Variational Transition State Theory with Optimized Multidimensional TunnelingThe Journal of Physical Chemistry A, 2001
- Adiabatic Connection for KineticsThe Journal of Physical Chemistry A, 2000
- 12C/13C kinetic isotope effects in the reactions of CH4 with OH and ClGeophysical Research Letters, 1997
- Current Status of Transition-State TheoryThe Journal of Physical Chemistry, 1996
- AB initio studies of the kinetic isotope effect of the CH4 + OH• atmospheric reactionGeophysical Research Letters, 1991
- A simple approximation for the vibrational partition function of a hindered internal rotationJournal of Computational Chemistry, 1991
- From Force Fields to Dynamics: Classical and Quantal PathsScience, 1990