Lattice dynamics of Ferroelectric TlInS2 crystal

In this paper we present the results of ab initio first-principle calculations of the lattice dynamics of ternary TlInS2 semiconductor with highly anisotropic crystal structure. Calculations have been performed using the open-source code ABINIT on the basis of density functional theory within the plane-wave pseudopotential approach. The basis of plane waves was truncated at electron kinetic energy of 40 Ha. Integration over the Brillouin zone was carried out using a 2 x 2 x 2 grid. The equilibrium structure was determined by minimizing the total energy with respect to the lattice constants and the internal structural parameters. The results are discussed in terms of previously existing experimental data. It is shown that along the layer, the low-frequency acoustic branch displays the bending wave behavior that is typical for crystals having a layered structure.