材料期刊网

The optical spectra and their pressure dependence for NiO crystal have been calculated by use of a modified crystal-field theory, where the normalization parameters N-t and N-e describe the covalency reduction of electronic interactions for t(2) and e orbitals and the pressure coefficients dN(t)/dP and dN(e)/dP are obtained from a cluster approach. The calculated results are in agreement with the observed values. The difficulty of the discrepancy in the change in Racah parameters B under pressure for the T-3(1a) and T-3(1b) transitions occurring in the conventional crystal-field theory is removed.