AN ABINITIO STUDY ON THE REACTION OF CH(X2-PI) WITH CH4

The mechanism of the reaction CH(X2pi) + CH4 has been investigated by ab initio molecular orbital calculations. Addition, insertion, and abs traction-addition reaction paths have been examined by, in total, five methods of approach. The addition reaction path has a rather high ene rgy barrier. Our calculations have implied that the assumed insertion reaction path does not seem to exist for the reaction CH + CH4, and a two-step mechanism (abstraction-addition reaction path) was then propo sed. For the abstraction-addition reaction, the reactants, transition state, intermediates, and products were optimized at the HF/3-21G and HF/6-31G levels, and vibrational frequencies were calculated at the H F/3-21G level. Electronic correlation energy was estimated by means of the Moller-Plesset perturbation theory and configuration interaction method. The excited-state abstraction reaction was also studied in som e detail.