R center states of LiF in the region of F and M bands

Abstract

The states of the R center which have transitions in the regions of the F and M bands., the RF and RM states respectively., are studied. The R center is taken., according to the model of Pick, as three F centers in an equilateral triangle configuration. The states are described by linear combinations of 2s and 2p Slater-type orbitals. The Heitler-London approach is used to construct the wave functions. In addition to the point-ion-lattice approximation, a pseudo-potential term is used to incorporate the structure of the nearest neighbors. A variational calculation is carried out and the RF transition is calculated to be 5.33eV and the RM transition is calculated to be 2.84eV. Both states are of symmetry type E. These values are within ten per cent of the observed values.