Interpretation of the 57Fe Isomer Shift by Means of Atomic Hartree–Fock Calculations on a Number of Ionic States

The Hartree–Fock method is used to calculate the values of ${\text{|\hspace{0.17em}Ψ(0)\hspace{0.17em}|}}^2$ for a number of configurations of different Fe ions. An interpolation formula for ${\text{|\hspace{0.17em}Ψ(0)\hspace{0.17em}|}}^2$ as a function of the occupation number of valence electron orbitals $\text{(3d, 4s, 4p)}$ is given. Experimental Mössbauer isomer shifts are correlated to estimated configurations which are compared to available MO calculations for a few cases.