Theoretical study of a Cu+ ion impurity in a NaF host

The Cu+ ion impurity in a NaF host has been modeled using a finite cluster of ions to represent the crystal lattice. Several approximations to the lattice potential in the region of the cluster were compared to the exact Madelung potential. The error in the calculated nearest-neighbor distance for the pure host was found to be proportional to the error in the lattice potential. Hartree–Fock calculations were carried out for the ground 1A1g and excited 1,3Eg and 1,3T2g states of the NaF:Cu+ system. The resulting energy level structure was compared to the experimental spectra. The symmetric-stretch potential energy curve, vibrational frequencies, and Franck–Condon factors were calculated for the 1A1g and 1,3T2g states. Using a single configuration coordinate model and a semiempirical spin–orbit coupling scheme, the relative intensities and bandwidths were calculated for absorption to the 1,3T2g states and compared to experiment.