Band structure and optical electron spectra of (TrMA)CoCl3·2H2O crystal

 DFT calculations of the band structure, density of states and optical spectra of trimethylammonium cobalt chloride dihydrate [(CH3)3NH]CoCl3·2H2O single crystal have been performed for the first time within a framework of the density functional theory using the CASTEP code (Cambridge serial total energy package). The valence band energy dispersion E(k) was found to be flat, although the bottom of the conduction band reveals noticeable dispersion along the lines [000]-[0012] and [-12012]-[-1200]-[-12120]. The calculations performed in the generalized gradient spin approximation (GGS) predict nonzero magnetic moment for the TrMA-CoCl3 crystal. The optical spectra calculated agree qualitatively with the experimental absorption spectra of the crystal in the range of Co ions excitation, 1.50-2.75 eV.