Nonadiabatic effects in the collision of F(2P) with H2(1Σg+). 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(²P_1/2)+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.