Classical trajectories using the full a b i n i t i o potential energy surface H−+CH4→CH4+H−

The classical trajectory method has been coupled with the gradient evaluation of the ab initio potential energy with respect to nuclear coordinates to study molecular dynamics. Trajectories, starting from a known transition state, can be computed in the full space of Cartesian coordinates in order to provide information on the reaction dynamics. The nucleophilic substitution reaction H−+CH4→CH4+H− is treated as an example and is shown to occur via a nonadiabatic path where initial vibrational energy of the methane molecule is essential for reaction.