Theoretical Investigations on the Off-Center Displacement of Co²⁺ in SrO by Analyzing Its Anisotropic g Factors

The off-center displacement of Co²⁺ ion in SrO crystal is investigated by analyzing its anisotropic g factors g_x, g_y and g_z through diagonalization of the 6×6 energy matrix within ⁴T₁ ground state for a 3d⁷ ion under rhombic symmetry. In the matrix, the contributions from the admixtures of various J(=1/2, 3/2, 5/2) states and the fourth-order term D_η of rhombic crystal-fields and the ligand orbitals and spin-orbit coupling interactions, which are usually ignored in the previous studies, are considered. Both g factors (g_x=4.172, g_y=5.004 and g_z=2.133) and the off-displacement value (ΔR≈0.023nm) show good agreement with the experimental data.