材料期刊网

The four optical band positions and six spin-Hamiltonian parameters (the g factors g(i) and the hyperfine structure constants A(i), i = x, y, z) for the rhombic Cu(2+) center in fi-Ca(3)(PO(4))(2) are calculated by two theoretical methods: the complete diagonalization (of energy matrix) method and the perturbation theory method (PTM). Both methods are based on the cluster approach, in which the covalence due to admixture of ligands to the central metal ion is considered. The calculated results of the two methods are close to each other and agree with the experimental values. This suggests that both methods are effective in explaining the optical and electron paramagnetic resonance data for d(9) ions in crystals. The calculations also show that although the admixture of vertical bar d(z)(2)> to the ground state wave function is small, it should not be neglected in calculations of spin-Hamiltonian parameters. So, in PTM, the high-order perturbation formulae of spin-Hamiltonian parameters based on the cluster approach for d(9) ion in rhombic symmetry should be derived by taking into account the admixture of the vertical bar d(z)(2)> state to the vertical bar d(x2-y2)> ground state.