Superhyperfine interactions and covalency contribution to axial zero field splitting for |MnF6|4− complexes in fluorides

An approximate L.C.A.O.-M.O. calculation based upon the one-electron ionic hamiltonian initially derived by Sugano and Shulman, gives satisfactory agreement with measurements of superhyperfine interactions at the ligand shell and outer shell nuclei, for Mn²⁺ in AMF₃ crystals, when one takes into account an external crystal potential acting on the |MnF₆|^4? complex. The results obtained for cubic symmetry are extrapolated to an independent bond model in order to discuss the covalency contribution to axial zero field splitting.