Charge transfer in H++He+and He2++H collisions

Charge transfer and excitation cross sections for H++He+ and He2++H collisions have been calculated for centre of mass energies in the range 2 to 200 keV, using a two-centre atomic expansion model in which 1s, 2s and 2p orbitals are retained about each nucleus. For the He2++H reaction close agreement is found with experiment up to about 60 keV, but for the inverse reaction, H++He+, agreement with experiment is found only at energies below about 15 keV. A comparison with the results of previous atomic and molecule expansion models is made.