Positron elastic scattering by a semifilled-shell atom*

Abstract

Abstract We theoretically study the positron elastic scattering by an atom with a multielectron semifilled subshell in its structure. We focus on gaining the initial insight into the specifics of such a process. The positron scattering by the Mn(…3d54s2, 6S) atom with a 3d5 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 the positron 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.