Theoretical studies of the g factors and local structure for the rhombic Fe+ center in NaF

The anisotropic g factors and local structure for the rhombic Fe+ center in NaF are theoretically studied using the perturbation formulas of the g factors for a rhombically distorted octahedral 3d7 cluster. The impurity Fe+ is found not to occupy exactly the host Na+ site in NaF but to experience the off-center displacement of about 0.28 Å along [1 1 0] axis due to size mismatch substitution. The calculated g factors based on the above impurity displacement show reasonable agreement with the experimental data. The local structure of the Fe+ center is discussed.