用从头算的UHF/6-31G方法、反应途径哈密顿理论以及变分过渡态理论,计算了反应CH_2(~3B_1)+H_2→CH_3+H的反应途径、沿反应途径的动态学性质和正则变分过渡态理论的速率常数.在此基础上,计算了振动选态反应的速率常数.结果表明:经典过渡态理论高估了反应速率常数,用变分过渡态方法处理效果明显;较低温度下考虑隧道效应更重要,而用小曲率近似的校正是有效的;H_2分子的振动激发对反应速率常数有较大增进. Using the ab initio UHF / 6-31G method, reaction path Hamilton theory and the theory of variational transition states, the reaction pathways, the kinetic properties along the reaction path and the canonical regularity of the reactions CH_2 (~ 3B_1) + H_2 → CH_3 + H The rate constants of the VE transition state theory are calculated. The rate constants of the vibrational VE state reaction are calculated. The results show that the classical transition state theory overestimates the reaction rate constant, It is more important to consider the tunneling effect at the temperature, while the correction with the small curvature approximation is effective. The vibrational activation of the H 2 molecule greatly improves the reaction rate constant.