The perturbation formulas of the electron paramagnetic resonance parameters g factors g||, g⊥ and the hyperfine structure constants A||, A⊥ were established for a 3d1 ion in tetragonally distorted octahedral, by including the contributions from the p-and s-orbitals as well as the spin-orbit coupling of the ligands based on the cluster approach. The related energy separations could be obtained from the superposition model and local structure of impurity center. These formulas were applied to the studies of the electron paramagnetic resonance parameters for the interstitial V4+ in anatase. The calculated results of the present work gave better agreement than did those of previous studies with the observed values. It was found that the contributions to the electron paramagnetic resonance parameters from the ligand orbitals and spin-orbit coupling interactions could not be neglected for systems with significant covalency.

Studies of the EPR Parameters of the Interstitial V4+ in Anatase. Wu, S.Y., Lin, J.Z., Fu, Q., Zhang, Z.H., Wei, L.H.: Journal of the University of Electronic Science and Technology of China, 2008, 37[4], 556-7