Coherence parameters for charge transfer in collisions of protons with helium calculated using a hybrid numerical approach

Abstract

We propose a method to describe charge transfer in ion–atom collisions that hybridizes the lattice, time-dependent Schrödinger equation (LTDSE) approach with the atomic-orbital coupled-channel technique. This method takes advantage of the completeness of the treatment of the collision problem through the LTDSE approach within a relatively small space around the distance of closest approach during the collision. It then extends the solution into the asymptotic regime through the less computationally intensive continuation of the time evolution of the electronic states under consideration utilizing a small, external coupled-channels expansion. This method is employed to calculate coherence parameters of an electron captured into the n = 2 shell of hydrogen in H++He collisions to illustrate its effectiveness. The results show excellent agreement with experimental measurements and constitute improvements over various existing theoretical treatments.