A simple ab initio calculation for energy transfer in collisions of hot hydrogen atoms with carbon dioxide

Abstract

Cross sections for excitation of the CO 2 v 3 asymmetric stretch vibration in collisions with 2.1 eV hydrogen atoms have been calculated within the vibrational close coupling rotational infinite order sudden (VCC-IOS) approximation. The intermolecular potential was assumed to be a pairwise additive atom-atom exponential repulsion with parameters fitted to theoretical SCF points. Predicted final rotational state distributions agree reasonably well with experimental data, as well as with predictions of a recently proposed breathing ellipsoid model. Predicted vibrational excitation rates, however, are one to two orders of magnitude too small, a failure which is attributed to the inability of a pairwise additive form to reproduce accurately the vibrational dependence of the potential.