Quantum reactive scattering via the S-matrix version of the Kohn variational principle: Differential and integral cross sections for D+H2 →HD+H

Abstract

A comprehensive survey of the quantum scattering methodology that results from applying the S‐matrix version of the Kohn variational principle to the reactive scattering formulation given by Miller [J. Chem. Phys. 5 0, 407 (1969)] is presented. Results of calculations using this approach are reported for the reaction D+H2 →HD+H. The 3‐d calculations include total angular momentum values from J=0 up to 31 in order to obtain converged integral and differential cross sections over a wide range of energy (0.4–1.35 eV total energy). Results are given for reaction probabilities for individual values of J, integral and differential cross sections for a number of energies, and state‐to‐state rate constants (i.e., a Boltzmann average over translational energy), and comparisons are made to a variety of different experimental results. A particularly interesting qualitative feature which is observed in the calculations is that the e n e r g y d e p e n d e n c e of the differential cross section in the b a c k w a r d d i r e c t i o n (θ=180°) shows a resonance structure (due to a short‐lived DH2 collision complex) which is very similar to that in the J=0 reaction probability. This resonance structure does not appear in the energy dependence of the integral cross section, being averaged out by the sum over J.