A theoretical study of the O(1D)+CH4 reaction I

The reactions are assumed to proceed through an insertion mechanism on the CH3OH ground state potential energy surface. The rate constants of CH3OH dissociation at a O(1D)+CH4 collision energy of 6.6 kcal/mol are obtained by the RRKM and variational RRKM theory based on our ab initio potential energy surface. The rate constants of the primary reactions suggest their branching ratios are in the order of OH>H>H2>H2O, consistent with the experimental findings. The predicted rate constant of the OH radical channel indicates a likely nonstatistical behavior. The derived bimolecular rate constant for O(1D)+CH4 at 300 K agrees reasonably well with the experiments.