Study on structural, mechanical, electronic, vibrational, optical and thermo-dynamical behaviour of ZB Structured BeZ (Z=S, Se and Te) using ATK-DFT

The present research is a systematic computational study focused on structural, mechanical, electronic, vibrational, optical and thermo-dynamical properties of zinc-blende (B3) structured beryllium chalcogenides BeZ (Z=S, Se, Te) compounds using ATK-DFT method using PZ and PBEsol exchange and correlation potentials within the local density approximation (LDA) and the generalized gradient approximation (GGA) respectively and their comparison. The k-point and energy cut-off values were tested and provided convergence in self-consistent calculations. The structural parameters such as lattice constant, bulk modulus, second order elastic constants (C11, C12, C44) and material properties (B, G, Y and σ) for these crystals are computed and discussed. To explain the electronic properties, electronic energy band structure, complex band structures, phonon band structure, phonon density of state and electron density distribution are plotted. The effect of pressure on elastic constant, material properties and phase transitions are also studied, including phase transition from ZB structure to NiAs appearing at 53 GPa, 49 GPa and 33 GPa for BeS, BeSe, and BeTe respectively.

Sound velocities and thermal properties of BeX (X=S, Se and Te) alkaline-earth chalcogenides

The sound velocities and some thermal properties of BeX (X=S, Se and Te) beryllium-chalcogenides large band gaps semiconductors have been estimated by employing some usual theoretical and emperical formulas. The lattice parameters and the elastic stiffness constants used here are taken from the literature. The longitudinal, transverse and average elastic wave velocities, the Debye temperature, the melting temperature, the thermal conductivity and the Grüneisen parameter are successfully predicted and analyzed in comparison with the available experimental and theoretical data. In general, our obtained results of these quantities agree well with the experimental and other theoretical data of the literature.