Electron translation and asymptotic couplings in low-energy atomic collisions

The calculation of cross sections for inelastic and charge-exchange atomic collisions encounters a principal difficulty. The coordinates used to describe the collision event are usually not appropriate for the description of the collision partners long before and after the collision. As a consequence, the coupling matrix elements that govern inelastic transitions can remain nonzero for large internuclear distance. We present a simple procedure to deal with this situation in the framework of a full quantum-mechanical treatment. It applies to radial as well as rotational coupling mechanisms. We demonstrate the practical applicability by numerical examples.