Perturbed Morse Oscillator Approximation in Reactive Collisions. II. A Repulsive Potential

Abstract

The H+Br2→HBr+Br reaction has been considered to form a linear collision intermediate and detailed reactive scattering cross sections have been computed quantum mechanically using a perturbed Morse oscillator approximation. These computations employed a diatomics-in molecules potential-energy surface distorted to make it moderately repulsive, i.e., the potential energy of the collision intermediate was made to be closer to that of the reactants than to that of the products. The resulting cross sections are peaked about the lower allowed vibrational quantum numbers of product HBr for a wide range of initial conditions corresponding to temperatures from 300° to 1000°K. This appearance of the heat of reaction as relative translation rather than as internal excitation is in agreement with both experiment and semiclassical calculations. Specific rate coefficients and pre-exponential factors calculated from the computed cross sections are also in satisfactory agreement with experiment.