Abstract:
Using the sublattice method and density functional theory, the electronic structure of a LiTlTe$_2$ crystal with the chalcopyrite structure was studied for the first time and the equilibrium parameters of the crystal lattice $a$ = 6.7526 $\mathring{\mathrm{A}}$, $c$ = 13.3037 $\mathring{\mathrm{A}}$, $u$(Te) = 0.2423 were calculated. It has been established that the valence bands of the LiTlTe$_2$ crystal and its closest analogue LiInTe$_2$ actually coincide in topology, and the LiTlTe$_2$ 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 LiInTe$_2$ and LiTlTe$_2$ 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 InTe$_4$ and TlTe$_4$. The vibrational modes and elastic constants are calculated, confirming the stability and mechanical stability of the LiTlTe$_2$ crystal.
Fulltext:
PDF file (1138 kB)