Influence of Variations of the Potential-Energy Surface on Exchange-Reaction Probabilities

Abstract

Accurate quantum‐mechanical reaction probabilities for the collinear reaction $\mathrm{H}+{\mathrm{H}}_2\to {\mathrm{H}}_2+\mathrm{H}$ on a series of parametric Wall—Porter potential surfaces have been determined by solving the relevant time‐independent Schrödinger equation using a newly developed close‐coupling technique. The effects of variations of (1) the total energy, (2) the classical activation energy (barrier height), (3) the curvature of the reaction path, and (4) the slope and ``width'' of the potential barrier along the reaction path on various attributes of the reaction are found by systematically changing selected parameters of the surface. The reaction attributes of chief interest are (1) the gross structure of the reaction probability curves (as a function of total energy), (2) the effective threshold for reaction, and (3) the degree of vibrational excitation of the product. The various effects induced in the reaction attributes by variations of the potential surface parameters are correlated and discussed. Several qualitative conclusions are drawn.