High-order perturbation formulae for electron paramagnetic resonance zero-field splittings D, E and g-factors for d3 ions in orthorhombic symmetry were established by using a 2-spin-orbit coupling parameter model in which contributions from the spin-orbit coupling of the central d3 ion and that of the ligands were included. Based upon these formulae, the electron paramagnetic resonance parameters for the Cr3+ ion at an orthorhombic defect site were calculated by considering a suitable defect-induced lattice distortion. The calculated values of D and E exhibited good agreement with observed values. The reasons for a disparity of the gi-shift Δgi = (gi-gs), between calculation and experiment, and the importance of contributions to the electron paramagnetic resonance parameters arising from the spin-orbit coupling of ligands were considered.

Theoretical Studies of EPR Parameters for Cr3+ Ion at an Orthorhombic Defect Site in AgBr Crystal. W.C.Zheng, S.Y.Wu: Physica Status Solidi B, 1999, 207[2], 429-35