Comparison of local exchange potentials for electron scattering by hydrogen molecules

Abstract

The elastic scattering and rotational excitation cross sections for e--H2 are calculated in the adiabatic nuclei approximation, using the 'semiclassical' and 'free-electron-gas' local exchange approximations. The integrated elastic scattering results are compared to calculations in which exchange was treated 'exactly', over the energy range of 0 to 20 eV. The semiclassical exchange approximation is found to agree best with the 'exact' results for energies above 6 eV. The differential elastic and rotational excitation cross sections, for the various local exchange approximations, are compared with experimental measurements and a similar semiclassical exchange calculation at 10 eV.