The present work deals with single electron capture processes from ${\mathrm{H}}_2$ targets by impact of heavy bare ions at intermediate and high collision energies. Within the distorted wave formalism, the one active electron model developed to describe collisions with multielectronic atomic targets is used for the case of ${\mathrm{H}}_2$ targets. Three different distorted wave models are employed: the continuum distorted wave, the continuum distorted wave–eikonal initial state, and the continuum distorted wave–eikonal final state. Using these distorted wave approximations, total cross sections for ${\mathrm{H}}^{+}$ and ${\mathrm{He}}^{2+}$ impact are calculated employing two different representations of the initial bound molecular wave function. The variation of the total cross sections due to this change in the description of the initial wave function and due to changes of the distortion factors in the entrance and exit channels is studied. The theoretical results are compared with available experimental data.

Electron excitation from monoelectronic targets by impact of bare ions from low intermediate to high collision energies is theoretically studied by using the symmetric eikonal approximation. In addition, multichannel semiclassical impact-parameter calculations are also carried out. Distortion effects introduced by the projectile charge are shown to appear in the theoretical models at low intermediate collision energies.

A complete form of the post version of the continuum distorted wave (CDW) theory is used to investigate the single ionization of multielectronic atoms by fast bare heavy ion beams. The influence of the non-ionized electrons on the dynamic evolution is included through a residual target potential considered as a non-Coulomb central potential through a GSZ parametric one. Divergences found in the transition amplitude containing the short-range part of the target potential are avoided by considering, in that term exclusively, an eikonal phase instead of the continuum factor as the initial channel distortion function. In this way, we achieve the inclusion of the interaction between the target active electron and the residual target, giving place to a more complete theory. The present analysis is supported by comparisons with existing experimental electron emission spectra and other distorted wave theories.

Different aspects of relativistic distorted-wave models for electron capture in ion-atom collisions are analyzed. In particular, the nonrelativistic limit of the matrix continuum distorted-wave approximation is studied for reactions with or without change in the electron spin.