Abstract: In this work, EPR spectra and optical absorption spectra of VO²⁺ in KZnClSO₄·3H₂O(PZCST): VO²⁺ single crystal were calculated theoretically based on the two-spin-orbit-coupling parameter model and the corresponding formulae of energy levels for the tetragonal symmetry of 3d¹ cluster. The calculated results were found in good agreement with experimental data. It was deduced from the results that the local symmetry structure along the C₄ axis is compressed tetragonal distortion with a size of 0.47 nm. The large value of κ indicates a large contribution from spin-polarize of unpaired electron to the hyperfine constant.

Key words: electron paramagnetic resonance (EPR), optical spectrum, two-spin-orbit-coupling parameter model, PZCST: VO²⁺