Electronic Structure of theUCenter. I. Optical Absorption and Lattice Relaxation

Abstract

The electronic structure of the $U$ center in KCl, KBr, and KI is calculated for the ground and first excited states using a model in which the interactions with the first-nearest-neighbor ions are taken into account in detail and all other ions are treated as point charges. A second, more refined model, which involves the electronic structure of all ions and polarization effects, is briefly described. It is used for calculations of the electronic structure, optical absorption, and lattice relaxation of the $U$ center in KCl.