Theoretical calculations of spin-Hamiltonian parameters for the square planer CuCl42- cluster in Cs2ZrCl6 crystal

The high-order perturbation formulas based on a two-mechanism model (where in addition to the contributions from the crystal-field (CF) mechanism in the usually-applied CF theory, those from the generally-neglected charge-transfer (CT) mechanism are also contained) are employed to calculate the spin-Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and the hyperfine structure constants A(parallel to), A(perpendicular to)) of the square planar CuCl42- clusters in Cs2ZrCl6 crystal. The needed CF energy levels in the calculations are obtained from the observed optical spectra. The calculated results show reasonable agreement with the experimented values. The negative sign of A(parallel to) and positive sign of A(perpendicular to) are proposed from the calculations. The calculations also suggest that one should take account of the contributions clue to both the CF and CT mechanisms for the exact and rational calculations of spin-Hamiltonian parameters of Cu2+-Cl- combination in crystals. (C) 2015 Elsevier B.V. All rights reserved.