Model potential treatment of C4++H2 collisions at low impact energies

We present cross sections for electron capture in C4+ + H-2 collisions in the energy range 50 eV amu(-1) less than or equal to E less than or equal to 6 keV amu(-1),calculated using a model potential aproximation to treat the interaction of the active electron with C-4(+) and H-2(+) cores and an equivalent-electron bielectronic interpretation of the probabilities. The limitations of this method are analysed by comparison with the two-electron ab initio treatment. Double-electron-capture cross sections are also calculated using ab initio and model potential treatments. We propose a modified independent particle model to evaluate single-electron-capture cross sections.