Nonadiabatic effects in the collision of F(2<i>P</i>) with H2(1Σ<i>g</i>+). III. Scattering theory and coupled-channel computations

Abstract

The theory of nonreactive atom–diatom collisions in the presence of multiple electronic surfaces is developed in both space-fixed and body-fixed coordinate frames. The formalism is applied to the scattering of fluorine atoms by para- and ortho-hydrogen molecules. Coupled-channel computations of integral cross sections for fine structure and rotational transitions are carried out in the rigid rotor approximation using ab initio self-consistent-field potential energy surfaces and are facilitated by the use of a diabatic representation of the molecular channel states. The magnitudes of the cross sections at a specific translational energy are found in general to decrease with increasing energy defect. For F(2P1/2)+p-H2 the cross section for a near resonant electronic-to-rotational energy transfer process dominates other inelastic transitions by at least an order of magnitude.