Polarisation effects in low-energy positron–molecule scattering

Abstract

The UK molecular R-matrix method has been adapted to treat positron collisions from polyatomic targets. A simple empirical enhancement factor which corrects for the underestimation of electron–positron polarisation and correlation effects in the calculations performed with the static-plus-polarization model at low scattering energies is presented. Application of this model to positron scattering from carbon dioxide at energies below 8eV is discussed. Introduction of the enhancement factor improves the integral cross sections significantly and introduces structures in the differential cross sections consistent with other studies. The prospects for a fully ab initio treatment of this problem are discussed.