Positron elastic scattering by a semifilled-shell atom

Abstract

We theoretically study the positron elastic scattering by an atom with a multielectron semifilled subshell in its structure. The positron scattering by the Mn(...3d4s,S) atom with a 3d semifilled subshell (e+Mn scattering) is chosen as a case study. We account for both the electron correlation and the formation of a e + e− virtual positronium (Ps) in the intermediate states of the e +Mn system. Electron correlation is taken into account in the framework of the self-energy part of the scattering positron Green function generalized for the application to semifilled-shell atoms. The influence of the virtual Ps formation on e+Mn scattering is taken into account by the reduction of the energy of the virtual positron plus atomic-excited-configuration states by the Ps-binding energy, to a reasonable approximation. We unravel the importance and specificity of the influence of both the virtual Ps and electron correlation on e +Mn elastic scattering. We demonstrate spectacular differences between the electron and positron scattering processes.