Computer Modeling of the Optical Properties of Transition-Metal Ions in Solids

Abstract

ABSTRACTComputational methods for modeling the optical properties of substitutional transition-metal impurities in insulating solids, potentially applicable to some scintillator and phosphor materials, are reviewed. Methods considered include crystal-field and semi-empirical ligand-field models; SCF-Xα-SW, SCF-RHF-LCAO, SCF-UHF-LCAO and CI ab initio methods: and ICECAP and HADESR embedded cluster methods with lattice relaxation. A detailed example of the application of the HADESR method to crystal-field spectra of Cr3+ in halide elpasolites is described. In this method, ab initio molecular-orbital calculations with effective core potentials are performed for selected ionic configurations. Simultaneous relaxation of the cluster and surrounding lattice, with mutual pair. potential interactions, is accomplished by a modified lattice statics program. Calculated properties include pressure-dependent optical transition energies, vibration frequencies and radiationless transition rates.