Quasiclassical Trajectory Study on the Role of CH-Stretching Vibrational Excitation in the F((2)P) + CHD3(v(1)=0,1) Reactions.

To analyze the role of CH-stretching vibrational excitation on the reactivity and dynamics of the F((2)P) + CHD3(v1=0,1) reactions, quasiclassical trajectory calculations using a full-dimensional analytical potential energy surface at different collision energies were performed. The extra energy of the CH excitation had almost no effect on the reactivity for the DF + CHD2 channel, although it increased the reactivity for the HF + CD3 channel, with the net effect being that CH excitation barely modified overall reactivity. In addition, the DF/HF branching ratio was not far from the statistical value for the ground-state reaction, whereas CH excitation decreased this ratio. These results, intimately related to the topology of the entrance channel, agree with recent theoretical results obtained using different surfaces (although some differences even persist among them) but strongly contradict recent experiments. This controversy will doubtless guarantee more accurate experiments and theoretical calculations in the future. However, properties related to the exit channel show reasonable theoretical/experimental agreement. Thus, the extra energy of CH excitation is mainly channelled into the HF and DF products for the HF + CD3 and DF + CHD 2 channels, respectively, and the product scattering distributions are forward in both channels, where CH excitation has almost no effect on them.