Sternheimer valence shielding and antishielding factors for some ions of interest in Mossbauer spectroscopy

Using nonrelativistic Hartree-Fock-Slater wave functions and Sternheimer's uncoupled perturbation-numerical method the valence shielding-antishielding factor R including exchange has been calculated for Cr, Mn+, Fe2+, Co3+, Ni4+ (all in 3d6 isoelectronic configuration), Ru2+ (4d6), Os2+ (5d6), Pr3+ (4f2), Tm3+ (4f12), and Np6+ (5f1) to be 0.26, 0.15, 0.12, 0.10, 0.08, -0.06, -0.12, 0.12, 0.18, and 0.01, respectively. The quadrupole splitting data on Fe2O3, Al2O3·Fe3+, yttrium iron garnet (Td and Oh Fe3+ sites), and FeSiF6·6H2O have been reinterpreted using more reliable values of Sternheimer shielding-antishielding factors to obtain Q(57Fem) as 0.154, 0.179, 0.146, 0.139, and 0.156 b, respectively. The repercussions of the changes in the charge spread of the 3d6 ions in the crystalline lattice on R have also been discussed