The covalent effect on the energy levels of d2 ions in tetragonal crystal

In contrast to the traditional method which is unsuitable for the prediction of optical for the transition metal ion in covalence and low-symmetry crystal, this paper reports a new method to investigate the optical properties of d2 ions in covalent and tetragonal crystals and provides a new energy matrix. By using the energy matrix, the variation of energy levels and of the energy-level splitting as the parameter ε are studied; the energy-levels calculated by energy matrix taking no account of crystal-field parameter B000 and by energy matrix taking account of B000 are compared. It was found that the effect of the difference of covalence factors Nt and Ne on the energy levels and the energy-level splitting is very important and cannot be neglected when the optical properties of d2 ions in strong covalent crystals are investigated; B000 has an important contribution to the energy levels and should not be neglected; the different covalence of t2 and e orbitals should be considered not only in the electrostatic repulsions part of the energy matrix but also in the crystal-field potential part of the energy matrix. The complete matrix is applied to calculate the energy-levels of GaP:V3+ semiconductor. The calculated results are in agreement with the experiment data.