The Effect of a Change of Charge: The Scattering of Low Energy Positrons by Hydrogen Molecules

Abstract

The lowest partial wave is calculated for low-energy e+−H2 scattering using the Kohn method. In order to obtain accurate results, it is necessary to use a trial function which includes basis functions containing the positron-electron distance as a linear factor, i.e. Hylleraas-type functions. The inclusion of such functions has a very significant effect on the low-energy total cross section, bringing it into agreement with experiment for incident energies less than about 2eV. It also brings the calculated value for the annihilation rate of thermal positrons much closer to the experimental value. Progress is also reported on the calculation of the lowest partial waves of ∑u + and ∏u symmetry. As far as we are aware, this is the first time that Hylleraas-type functions have been used in a molecular scattering calculation.