Atomic orbital expansion study of electron capture in H++Li and He2++Li collisions

A modified two-centre atomic orbital expansion is used in an investigation of electron capture in collisions of H + and He 2+ ions with Li atoms. The calculated total and partial transfer cross sections constitute the first published origin-independent results in the energy range 0.5-20 keV for H + +Li and in the range 0.1-2.0 keV amu -1 for He 2+ +Li collisions. Total capture cross sections agree well with experimental data wherever the measurements have led to a consistent picture among themselves. For He 2+ +Li collisions, low-energy capture cross sections are predicted to be much larger than is indicated by results from two-state molecular orbital calculations without translational factors.