Phonon and Elastic Properties of TlIn3S5 Crystals: Experiment and Calculations from First Principles

Abstract Phonon properties of monoclinic TlIn3S5 crystals were studied using density functional perturbation theory and Raman spectroscopy methods. The dispersion of phonon modes, partial densities of states and frequencies of optical phonons in the center of the Brillouin zone were calculated, showing good agreement with experiment. All 13 elastic constants are determined from first principles, and the lattice stability criteria are shown to be met. The elastic moduli, Poisson’s ratio, acoustic wave velocities, Debye temperature and Grüneisen parameter were calculated. In the range of 0–400 K, temperature dependences of a number of thermodynamic functions of the compound were obtained.