The Influence of Lattice Vibrations on Spin-Correlated Crystal Fields I: An Intersite Mechanism for a Dynamic Lattice

Abstract

The role of lattice vibrations in providing additional contributions to spin correlated crystal fields has been investigated in the context of the calculation of zero field splittings for S-state ions. A many-electron theory, due to Stevens, which was originally developed to study exchange interactions in magnetic insulators has previously been used to study inter-site modifications to spin-correlated crystal fields in a static lattice. The present paper develops a methodology for the incorporation of lattice vibrations using a similar technique and an iterative form of perturbation theory for effective operators.