Charge transfer calculations using switching functions

Cross sections are presented for the charge transfer processes 4 He 2+ +H(1s) to 4 He + (2s)+H + and 4 He 2+ +H(1s) to 4 He + (n=2)+H + calculated using atomic basis functions which contained electron translation factors incorporating a switching function. The laboratory energy range was 0.25-200 keV amu -1 . Comparison with cross sections for the processes reveals that above about 2.5 keV amu -1 the switching function cross sections begin to exceed the plane-wave cross-sections, the discrepancy being considerable at high collision energies.