Application of the two state approximation to positronium formation in hydrogen

Abstract

A generalized form of Band's theory for rearrangement collisions based on the two state approximation in time dependent quantum-mechanical formalism is used to investigate the positron hydrogen charge exchange problem. The formalism takes into account the nonorthogonality of the rearrangement channel. The effect of nonorthogonality is to raise the cross sections from first Born results. At high energies our results approach Born results. Comparison with other calculations is also reported in the energy region 1.5 to 10 Ry.