New quantum-dynamical approximation for light-heavy-light chemical reactions in three dimensions

Abstract

Quantum-dynamical calculations on the three dimensional

reaction have been carried out. The method described in the previous paper is used. This involves applying the energy sudden approximation to the entrance channel hamiltonian, and the centrifugal sudden approximation to the exit channel hamiltonian. Results of vibrational-rotational product distributions, integral and differential cross sections, together with rate coefficients, are reported. The calculations have been performed using both a LEPS potential energy surface of Valencich et al., and a DIM surface of Last and Baer. The results for the LEPS surface agree well with those obtained in previous quasiclassical computations for this surface. The differential cross section for the strongly anisotropic DIM surface is purely in the backward scattering region, and agrees well with that obtained in a molecular beam experiment by McDonald and Herschbach. The differential cross section for the less anisotropic LEPS surface is distributed in both the backward and forward regions. The calculated room temperature rate coefficient for the DIM surface is only a factor of two above the value deduced from the experiments of Klein and Veltman, and Heidner and Bott. The LEPS rate coefficient, however, is larger than the experimental estimate by a factor of twenty.