Optimised translation factors for low energy proton-hydrogen-atom collisions

Abstract

The low energy proton-hydrogen-atom collision is described by an expansion in the 1s sigma g, 2p sigma u, 2p pi u molecular orbitals accompanied by phase factors depending on the electronic coordinate, which considers the electronic density flux set up by the nuclear motion on each orbital. These phase factors are strongly dependent on the original state; their effect on the probability of excitation to the 2p1 level is smaller than that obtained by using plane-wave phase factors, which overestimate the electronic translational momentum. The resulting probability of charge exchange agrees with other theoretical approaches and also with experiment in the range of collision energies and impact parameters where an expansion in rotating molecular orbitals such as the one described is justified.