Excitation and charge transfer in proton-lithium collisions at 5–15 keV

Excitation and charge-transfer cross sections for collisions of protons with lithium are calculated by direct solution of the time-dependent Schr\"odinger equation on a three-dimensional Cartesian lattice. For 5--15-keV incident energies the 1s² core of lithium may be treated effectively using a pseudopotential. For a proton incident on lithium, projections of the time-evolved wave function onto the lattice states of lithium yield excitation cross sections for the Li(2s)→Li(2p,3l) transitions. For lithium incident on a proton, projections of the time-evolved wave function onto the lattice states of hydrogen yield charge-transfer cross sections for the Li(2s)→H(2l,3l) transitions. The Li(2s)→Li(2p) excitation and Li(2s)→H(2s,2p) charge-transfer cross sections are found to be in good agreement with the crossed-beams experimental measurements of Aumayr et al. [J. Phys. B 17, 4185 (1984); 17, 4201 (1984); 18, 2493 (1985)].