Investigation of the electronic structure, hyperfine interactions, and radial densities in the iron tetrahedral sulfides with the use of the multiple-scatteringXαmethod

Abstract

Spin-polarized multiple-scattering and the Slater $X\ensuremath{\alpha}$ local-exchange calculations have been performed on the tetrahedral Fe${\mathrm{S}}_{4}^{4\ensuremath{-}}$, Fe${\mathrm{S}}_{4}^{5\ensuremath{-}}$, and Fe${\mathrm{S}}_{4}^{6\ensuremath{-}}$ clusters. The calculated charge and spin densities at the Fe nucleus have been used to interpret the M\"ossbauer hyperfine parameters. The calculated energy levels and iron $3d$ and $4s$ population were used to explain the $4s$ contribution, the measured magnetic moment, the observed crystal-field transition, and the large reduction of the free-ion Fermi-contact term.