Electronic structure and spectrum of Cr3+ in LiCaAlF6

Abstract

The electronic structure and spectrum of Cr3+ in LiCaAlF6 are investigated by using the discrete variatitional-local density functional (DV-LDF) method with embedded cluster model. The clusters (CrF6)3− withC3,D3d andOh point group symmetries embedded in the crystal are treated. The one-electron energy levels, densities of states, orbital populations, spin polarization splittings and energies of some terms are calculated. The results show that the relaxation of F− ions around the Cr3+ impurity is inevitable, and that theD3d andOh (CrF6)3− clusters, with an extended bond-lengthR(Cr−F) chosen to be equal to 1.88 A can represent this relaxation in a much better way. All the ligand-field transition energies, which are obtained from the transition-state energy and the Griffith parameters, as yielded by a restricted one-electron DV-LDF calculation, compare well with the experimental ones.