The reaction path of the reaction CH(^4∑^-)+H2O→CH2(^3B1)+OH is traced with Fukui's theory of intrinsic reaction coordinate by using ab initio MO method with gradient technique. On the basis, the dynamical properties along the reaction path and CVT (canonical variational theory) rate constants with correction of tunneling effect are investigated by reaction path Hamiltonian theory and variational transition state theory. The results show that the effects of electron correlation energy to the activation barrier are notable, the recrossing and tunneling effects exist and the corrections by means of CVT method and small curvature approximation method respectively are efficient.

Key words: AB INITIO CALCULATION, REACTION RATE CONSTANT, TRANSITION STATE THEORY, METASTABLE STATES, METHENYL-