The Spectrum and EPR Parameters of NiSiF₆·6H₂O Crystals

By means of a complete configuration mixing EPR theory for d³-C_3V complex ions and from the eigenvalues and eigenvectors of its complete configuration interaction strong field matrix for d³-C_3V^*, the optical and EPR spectra of the NiSiF₆·6H₂O crystals are analysed theoretically and systematically. Using only one set of spectral parameters for each temperature, the optical spectrum fine structure, the ground state spin-Hamiltonian parameters and the EPR conditions （H,\widetildev） are calculated harmoniously and uniformly for the first time and the results are in quite good agreement with experiments. The theoretical analyses show that the temperature-dependence of the zero-field splitting parameter D and the paramagnetic g-factors can be attributed to the linear temperature- dependence of the trigonal field parameter a.