Ab initio study of electronic, vibrational and elastic properties of LiInTe-=SUB=-2-=/SUB=- and LiTlTe-=SUB=-2-=/SUB=- crystals

Abstract

Using the sublattice method and density functional theory, the electronic structure of a LiTlTe2 crystal with the chalcopyrite structure was studied for the first time and the equilibrium parameters of the crystal lattice a=6.7526 Angstrem, c=13.3037 Angstrem, u(Te)=0.2423 were calculated. It has been established that the valence bands of the LiTlTe2 crystal and its closest analogue LiInTe2 actually coincide in topology, and the LiTlTe2 crystal is a direct-gap semiconductor with a band gap of 0.63 eV and a crystal splitting of 0.04 eV. The partial contributions of the density of states are analyzed and the features of the formation of the valence and conduction bands of LiInTe2 and LiTlTe2 crystals due to the contributions of their sublattices are revealed: the structure of the valence bands of both crystals is completely determined by the interaction in the cationic tetrahedra of InTe4 and TlTe4. The vibrational modes and elastic constants are calculated, confirming the stability and mechanical stability of the LiTlTe2 crystal Keywords: LiInTe2, LiTlTe2, chalcopyrite, electronic structure, sublattice.