The distortion of the tetragonal V2+-VM center in V2+-doped crystals was estimated by analyzing the electron paramagnetic resonance data according to 2 theoretical models. One was the 2-spin-orbit parameter model, where the contributions to electron paramagnetic resonance parameters from both the spin-orbit coupling of the central metal ion and that of the ligands were considered. The other was the conventional 1-spin-orbit parameter model, where only the contribution from the spin-orbit coupling of the central metal ion was included. The results from the 2-spin-orbit parameter model were more than 10 times those of the 1-spin-orbit parameter model.

Tetragonal Distortion of the Tetragonal V2+-VM Center in KBr:V2+ Crystal. W.C.Zheng, S.Y.Wu: Journal of Physics and Chemistry of Solids, 1998, 59[6-7], 903-5