Featured trends in e$^{-}+$Mn electron elastic scattering

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 $\epsilon= 0-25$ eV. Corresponding elastic scattering phase shifts $\delta_{\ell}(\epsilon)$ as well as partial $\sigma_{\ell}(\epsilon)$ and total $\sigma(\epsilon)$ 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 $\delta_{\ell}(\epsilon)$s, $\sigma_{\ell}(\epsilon)$s, and $\sigma(\epsilon)$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 $\Sigma$ 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 $\Sigma$. 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 $\sigma^{\downarrow}(\epsilon)$ near $\epsilon \approx 8$ eV but the absence of such in $\sigma^{\uparrow}(\epsilon)$ in e$^{-}+$Mn scattering is predicted.