United calculation of the optical and EPR spectral data for Co2+-doped CdS crystal

Abstract

This article reports a united calculation of the optical band positions and EPR parameters (g factors g//, g⊥ and zero-field splitting D) for Co2+ ion at the trigonal tetrahedral Cd2+ site of CdS crystal by using the complete diagonalization (of energy matrix) method built on the cluster approach. In the approach, the one-electron basis functions are the molecular orbitals composed of the d orbitals of central dn ion and p orbitals of ligands (rather than only the pure d orbitals in the conventional crystal-field theory), and so the contributions from not only the spin-orbit parameter of dn ion, but also that of ligand ion are contained. The calculated results are in rational agreement with the twenty-two (nineteen optical band positions and three EPR parameters) observed spectral values found in the literature. The defect structure (particularly, the angular distortion) of the trigonal Co2+ center in CdS: Co2+ is also acquired by the calculation. The outcomes are discussed.