Effect of crystal fields and self-consistency on dipole and quadrupole polarizabilities of closed-shell ions

Abstract

Dipole and quadrupole polarizabilities have been studied for 40 closed-shell ions in crystals including the influence of both the environment in the crystal and self-consistency. The effect of the crystal environment is incorporated by the Watson sphere model, while consistency effects are included by a procedure adapted from many-body perturbation theory. Both effects are found to be of importance and, when included, lead to satisfactory agreement with available experimental data on dipole polarizabilities. The influence of consistency effects is always found to reduce the polarizabilities with respect to the free ions while the influence of the crystal environment leads to a decrease for anions and an increase for cations. Comparison is also made for free ions with experimental results, and with theoretical results from other approaches to focus on the accuracy of calculated consistency contributions. Physical reasons are discussed for the observed trends in the various contributions to the polarizabilities for both free ions and ions in crystals.