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

A rather simple semiclassical model is described for treating short-ra nge correlation forces in the scattering of positrons from atoms at th e energies below the thresholds of positronium formation in each of th e considered systems. The present model allows one to introduce a none mpirical procedure for devising several damping functions, one for eac h of the perturbation terms which are included in the asymptotic expan sion of the polarisation potential. It is shown by calculations, carri ed out for He, Ne and Ar as examples, that one can obtain very good ag reement with experimental findings for surprisingly little computation al effort, even for fairly complex atomic targets which would be other wise out of reach for all but the most computationally intensive ab in itio methods.