COUPLED-CHANNEL CALCULATIONS WITH CARTESIAN GAUSSIAN-BASIS FUNCTIONS FOR H+HE AND HE++HE REACTIONS

The three-electron systems H + He and He+ + He are treated in the semiclassical approximation. The nuclei are described classically moving on straight-line trajectories and the electrons quantum mechanically by solving time-dependent coupled channel equations. As physical basis states we use products of H, He+ and He states with proper translation factors and completely antisymmetrized wavefunctions. In order to calculate the matrix elements of the electron-electron interaction analytically as far as possible, we expand the wavefunctions into Cartesian Gaussian basis functions. In the energy range E(lab) = 2-300 keV for H + He and E(lab) = 10-600 keV for He+ + He we present cross sections for excitation, charge transfer and ionization and compare them with various experimental data and other theoretical calculations.