Critical analysis of the band-shape function of a molecular system imbedded in a host crystal: Application to F centers

Abstract

We present an investigation of the accuracy of the saddle-point method in application to band-shape functions and find that it gives excellent results for most commonly encountered situations. We also present a comparison with a new improved short-time approximation which shows promise in applications. We use this new method to examine the behavior of the band-shape function in a distorted oscillator model. As an application, we have used these methods to explain the absorption and emission spectra of an F-center defect (a prototype defect system) in four different host crystals KCl, KI, KBr, and NaCl.