arXiv2013
The impacts of both exchange interaction and electron correlation, as well as their combined impact, on electron elastic scattering off a semifilled shell Mn(...$3d^{5}$$4s^{2}$, $^{6}S$) atom are theoretically studied in the electron energy range of $ε= 0-25$ eV. Corresponding elastic scattering phase shifts $δ_{\ell}(ε)$ as well as partial $σ_{\ell}(ε)$ and total $σ(ε)$ cross sections are found to be subject to a strong correlation impact. The latter is shown to be drastically different for oppositely spin-polarized scattered electrons, in some cases, thereby bringing significant differences in corresponding $δ_{\ell}(ε)$s, $σ_{\ell}(ε)$s, and $σ(ε)$s between said electrons. This is proven to be an inherent features of electron scattering off a semifilled shell atom in general. Electron correlation is accounted for in the framework of the self-energy part $Σ$ of the Green function of a scattered electron concept. The latter is calculated both in the second-order perturbation theory in the Coulomb interelectron interaction as well as beyond it by solving the Dyson equation for $Σ$. The significance of the "Dyson" correlation corrections in e$^{-}+$Mn scattering is unraveled. They are shown to aggravate noticeably the inherent differences between elastic scattering phase shifts and cross sections of spin-up ($\uparrow$) and spin-down ($\downarrow$) polarized electrons scattered off a spin-polarized Mn atom, in some cases. In particular, the existence of a narrow resonant maximum in $σ^{\downarrow}(ε)$ near $ε\approx 8$ eV but the absence of such in $σ^{\uparrow}(ε)$ in e$^{-}+$Mn scattering is predicted.