Mössbauer isomer shifts inZn++67andNi++61nuclei

Abstract

M\"ossbauer charge density for $^{61}\mathrm{Ni}^{++} (3{d}^{8})$ is calculated using Hartree-Fock wave functions. All the core $s$ functions ${\ensuremath{\varphi}}_{\mathrm{ns}} (n=1,2, \mathrm{and} 3)$ of ${\mathrm{Ni}}^{++}$ and their overlaps with six ${\mathrm{O}}^{\ensuremath{-}\ensuremath{-}}$ arranged in an octahedron corresponding to NiO are calculated as a function of interatomic distance $R$. Similar calculations for $^{67}\mathrm{Zn}^{++}$ in a tetrahedral environment of ${\mathrm{O}}^{\ensuremath{-}\ensuremath{-}}$ ions, appropriate to ZnO, are also performed. It is found that the isomer shift is given approximately by a "power law" $\ensuremath{\sim}{R}^{\ensuremath{-}7}$.