Convergence study of He2++H and He++H+charge exchange cross sections using a molecular approach with an optimised common translation factor

A convergence study of cross sections is reported for electron transfer in He 2+ +H and He + +H + collisions, using a molecular approach with up to ten (1 s sigma , 2 p sigma , 2 s sigma , 2 p pi ; 3 d sigma , 3 d pi , 3 p sigma , 4 f sigma , 4 f pi , 5 g sigma ) basis functions and a common translation factor (CTF) which was optimised according to the norm criterion. The energy ranges investigated are 0.75-16 keV amu -1 (He 2+ +H) and 5-80 keV amu -1 (He + +H + ). Conclusions are drawn from the excellent agreement between these results and those of considerably more involved calculations with plane-wave translation factors, and the persisting small discrepancy between theoretical and measured sigma (2sHe + ) cross sections is discussed.