First principles studies of the structural, electronic and optical   properties of LiInSe2 and LiInTe2 chalcopyrite crystals
  Detailed first principles calculations of the structural, electronic and optical properties of two representatives of the chalcopyrite group of compounds (LiInSe2 and LiInTe2) are reported in the present paper. Both materials are shown to be the direct band gap semiconductors. Analysis of the electronic properties showed that the degree of covalency increases if Se is substituted by Te. Calculations of the optical properties of both crystals allowed getting reliable approximation of the refractive index as a function of the wavelength. All calculated results were compared with the available experimental data; good agreement was demonstrated. 
C.-G.Ma, M.G. Brik
cond-mat.mtrl-sci