Hyperfine interaction of F‐centres in alkali‐halide crystals

Abstract

The Fermi contact term of the hyperfine interaction is calculated for the first eight shells of ions surrounding the F‐centre in KCl. The smooth part of the F‐centre wave function is taken from earlier work of Wood and Öpik and contains a g‐like component which, though small, appears to be necessary for understanding the details of the interaction. A symmetrical orthogonalization procedure is used to construct orthogonal “core” orbitals from free‐ion Hartree‐Fock functions. The importance of this step is demonstrated. The overall agreement with the experimental results is good, and therefore it is concluded that these results can be explained by detailed calculations with appropriate vacancy‐centred wave functions.