Electron-impact ionization ofH2using a time-dependent close-coupling method

Abstract

Electron-impact ionization cross sections for ${\mathrm{H}}_{2}$ are calculated using a nonperturbative time-dependent close-coupling method. In a standard frozen-core approximation, the six-dimensional wave function for the valence target electron and the incident projectile electron is expanded in products of rotational functions. The time-dependent Schr\"odinger equation for the two-electron system is then reduced to a set of close-coupled partial differential equations for the four-dimensional expansion functions in $({r}_{1},{\ensuremath{\theta}}_{1},{r}_{2},{\ensuremath{\theta}}_{2})$ center-of-mass spherical polar coordinates. The nonperturbative close-coupling results are found to be over a factor of 2 lower than perturbative distorted-wave results, but in excellent agreement with experimental measurements, at incident electron energies near the peak of the total integrated cross section.