ON A PARAMETER-FREE MODEL FOR TREATING POLARIZATION FORCES IN POSITRON SCATTERING PROCESSES

A rather simple semiclassical model is described for treating short-range correlation forces in the scattering of positrons from atoms at the energies below the thresholds of positronium formation in each of the considered systems. The present model allows one to introduce a nonempirical procedure for devising several damping functions, one for each of the perturbation terms which are included in the asymptotic expansion of the polarisation potential. It is shown by calculations, carried out for He, Ne and Ar as examples, that one can obtain very good agreement with experimental findings for surprisingly little computational effort, even for fairly complex atomic targets which would be otherwise out of reach for all but the most computationally intensive ab initio methods.