Theoretical analysis of electron capture and electron loss in Be4++H2 and H++H2 collisions

Dynamical calculations are carried out within the framework of the Frank-Condon approximation, for collisions between H+ and Be4+ ions with H-2 molecules within the range of energies 0.05 less than or equal to E less than or equal to 625 keV amu(-1). For the higher impact energies, we employ single-particle models, using semiclassical and classical trajectory Monte Carlo adapted methods. The accuracy of the single-particle models is checked by comparing molecular data, transition probabilities and cross sections, with those obtained with an ab initio approach and with experiment. We conclude that a central potential approximation for the H-2 molecule yields accurate capture and electron-loss cross sections for E greater than or equal to 0.5 keV amu(-1),and good ones in the energy region 0.1 less than or equal to E less than or equal to 0.5 keV amu(-1). An analysis of the equivalent and non-equivalent-electrons bielectronic interpretations of the model potential probabilities has been performed; for both reactions, comparison of the Hamiltonian matrix elements in a diabatic representation supports the conclusion that an equivalent-electron picture is adequate to describe the active electron of the H-2 molecule with an H-2(+) 'core'.