Constant centrifugal potential approximation for atom–diatom chemical reaction dynamics

The constant centrifugal potential approximation (CCPA) is generalized so as to be applicable to the reactions of rotationally excited reactants. The accurate calculations of reaction probabilities are required only for J≤‖Ω_i‖_MAX(≤j_i), where J is the total angular momentum quantum number, j_i represents the initial rotational state of a reactant diatomic molecule, Ω_i is the z component of J in the body‐fixed frame in the initial arrangement and ‖Ω_i‖_MAX is the maximum of such ‖Ω_i‖’s that give significant contributions to the reaction. The method is applied to the D+H₂(v_i=0,j_i) reaction with use of the hyperspherical coordinates, and is proved to be useful by comparing the results with those, of the authors’ own accurate calculations. The reaction mechanisms are clarified with respect to the dependence on Ω_i and j_i.