Effects of reagent vibrational excitation on the dynamics of the H + CHD3 → H2 + CD3 reaction: a seven-dimensional time-dependent wave packet study.

Seven-dimensional time-dependent wave packet calculations were carried out to study the title reaction on the potential energy surface constructed recently by the group [Y. Zhou, B. Fu, C. Wang, M. A. Collins, and D. H. Zhang, J. Chem. Phys. 134, 064323 (2011)]. Total reaction probabilities and integral cross sections were calculated for a number of initial vibration states. It is found that the fundamental C-H stretching excitation can promote the reaction dramatically. At E = 1.53 eV, it enhances the integral cross section by a factor of 13.2, which is in good agreement with the quasiclassical trajectory result on the ZBB1 potential energy surface, but larger than that on the the EG-2002 potential energy surface. The thermal rate constants were obtained for the title reaction by taking into account the contributions from all relevant initial vibration states. It is found that the ground initial state has a dominant contribution to the thermal rate constant at low temperature region. As the temperature increases, the relative contribution to the thermal rate constant from the ground initial state decreases quickly, and those from the stretching and bending excited states increases substantially. It is estimated that the C-H stretching mode contributes about 40% of the thermal rate constant at T = 1000 K despite the fact that the overall population for stretching excited states is tiny.