An exploratory study of reactant vibrational effects in CH3 + H2 and its isotopic variants

An empirically calibrated potential energy surface, obtained previously J. Chem. Phys. 61, 21 (1974), was used in a trajectory study of the effect of reactant energy partitioning on cross section for CH3 + H2 → CH4 + H. Artificial variations in the barrier position, and artificial and naturally occuring changes in the H masses, were also made. For natural CH3 + H2, H2 vibration enhances and CH3 out-of-plane bending depresses the cross section, at constant (25 kcal) translational energy of approach. The isotope substitution and barrier position effects are more complex and not predictable from triatomic A + BC generalizations. The relationship of these results to experimental ones is discussed.