Theoretical total charge transfer cross sections and differential ionization cross sections for ion–atom collisions illustrated for the p+Hp+H system

After three decades of intensive study PSS, CTMC, CDW and FHBS methods have emerged as acceptable methods for calculating cross sections for ion–atom collisions. Herein we focus on total theoretical cross sections for charge transfer in the p+Hp+H system. We find non-trivial differences.FHBS calculations are presumably the most accurate if driven to convergence. But the large basis two centered expansions, needed to treat accurately final state interactions with the projectile, are very expensive in computer time. We present a new method, E-AE-A theory, which is an order of magnitude more efficient.Differential direct ionization cross sections are generally well described by CTMC and CDW methods. But at 20 keV proton energy, evidence is emerging of the importance of a quantal interference effect wherein the scattered electron diffracts around the projectile and target.