Excitation and ionization in H(1s)-H(1s) collisions

Hydrogen atom-hydrogen atom scattering is a prototype for many of the fundamental principles of atomic collisions. In this paper we present an approximation to the H+H system for scattering in the intermediate energy regime of 1-100 keV. The approximation ignores electron exchange and two-electron excitation by assuming that one of the atoms is frozen in the 1s state. We allow for the evolution of the active electron by numerically solving the 3D Schroedinger equation. This approximation is by nature most appropriate for higher-energy collisions. The results capture many features of the problem and are in harmony with recent theoretical studies. Excitation and ionization cross sections are computed and compared with other theory and experiment. New insight into the mechanism of excitation and ionization is inferred from the solutions. (author)