First principles study of electronic structure and optical properties of LiMTe2 (M=Al, Ga, In) crystals

The results of first principles calculations of the electronic band structure, density of states and frequency dependent dielectric functions of LiAlTe₂, LiGaTe₂ and LiInTe₂ chalcopyrite crystals are reported. The calculations have been carried out within the density functional theory using norm-conserving pseudopotentials and a plane-wave basis. The peculiarities of the imaginary part ε₂(ω) of the complex permittivity are discussed and interpreted on the basis of the obtained band spectra. Our calculations show that the Ga-containing compound is characterized by the largest optical anisotropy compared to Al- and In-containing compounds and, therefore, is the most promising candidate for nonlinear optical applications among considered crystals.