Theoretical Investigation on Excitation, Ionization and Capture in H(1s,2s) +H(1s, 2s) Collisions

Cross sections of electron-loss in H(1s)+ H(1s) collisions and total collisional destruction of H(2s) in H(1s) + H(2s) collisions are calculated by four-body classical-trajectory Monte Carlo (CTMC) method and compared with previous theoretical and experimental data over the energy range of 4--100keV. For the former a good agreement is obtained within different four-body CTMC calculations, and for the incident energy E_p>10keV, comparison with the experimental data shows a better agreement than the results calculated by the impact parameter approximation. For the latter, our theory predicts the correct experimental behaviour, and the discrepancies between our results and experimental ones are less than 30%. Based on the successive comparison with experiments, the cross sections for excitation to H(2p), single- and double-ionization and H^- formation in H(2s)+H(2s) collisions are calculate in the energy range of 4--100keV for the first time, and compared with those in H(1s)+H(1s) and H(1s)+H(2s) collisions.