Electronic structure and optical properties of the impurityCu+in NaF

The electronic structure of the impurity ${\mathrm{Cu}}^{+}$ in a sodium fluoride crystal has been studied using the ICECAP (ionic crystal with electronic cluster, automatic program) methodology, which treats the defect and its vicinity quantum mechanically as a molecular cluster embedded in a shell-model lattice. The electrons in the cluster have been treated in the unrestricted Hartree-Fock self-consistent-field approximation, corrected for correlation by use of the many-body perturbation theory. The surrounding infinite lattice has been described by the shell model that incorporates host polarization and distortion self-consistently. The basis sets used to describe the ${\mathrm{Cu}}^{+}$ ion were optimized. The excitation energy and the crystal-field splitting were computed as 4.02 and 0.31 eV, respectively, versus the corresponding experimental results of 4.20 and 0.35 eV, respectively.