Calculation and Interpretation of the 129I Isomer Shifts in the Alkali Iodide Lattices

Abstract

Starting with an ideal alkali halide lattice composed of closed‐shell ions, the overlap and electrostatic interactions are computed between the nearest and next‐nearest neighbors in the alkali iodide lattices. The electrostatic perturbation on the s electrons is found to be small relative to the overlap deformation of the free‐ion wavefunctions. Both effects predict the same correct dependence for the relative isomer shifts, however. The deformed free‐ion wavefunctions are used to compute the relative isomer shifts at ¹²⁹I in the alkali iodide lattices. The value of the nuclear parameter in ¹²⁹I is ΔR/R=0.5×10⁻⁴.