Electronic structure of the Cu+ impurity center in sodium chloride

Abstract

The multiple‐scattering Xα method is used to describe the electronic structure of Cu+ in sodium chloride. Several improvements are brought to the conventional Xα calculation. In particular, the cluster approximation is used by taking into account external lattice potential. The ’’transition state’’ procedure is applied in order to get the various multiplet levels. The fine electronic structure of the impurity centers is obtained after a calculation of the spin–orbit interactions. These results are compared with those given by a modified charge‐consistent extended Hückel method (Fenske‐type calculation) and the merit of each method is discussed. The present calculation produces good quantitative agreement with experiment concerning mainly the optical excitations and the emission mechanism of the Cu+ luminescent centers in NaCl.