Test of local model potentials for positron scattering from rare gases.

Abstract

We report calculations of differential and integral cross sections for positron (${\mathit{e}}^{+}$) scattering from He, Ne, Ar, Kr, and Xe rare gases. An optical-potential approach is employed in which the repulsive Coulombic interaction is calculated exactly at the Hartree-Fock level and the attractive polarization and correlation effects are included via a model potential determined from the use of a local density-functional theory (DFT). These model calculations are further compared with the results from two other local potentials, one based on determining the short-range correlation energy, ${\mathit{E}}_{\mathrm{C}}$, for a positron in an homogeneous electron gas and the other from the correlation-polarization potential of an electron interacting with a free-electron gas. We found that the present DFT-based, correlation-polarization treatment is fairly simple to implement computationally and appears to be the most accurate of all the models examined here. Our results are in fact compared with recent measurements of differential and integral cross sections for positron scattering with rare gases and are found to be remarkably close to both sets of experiments.