DFT calculations of thermo-mechanical properties of Be-chalcogenides

Abstract

Beryllium chalcogenides (BeS, BeSe and BeTe) belonging to group II–VI compound semiconductor family crystallize in the zinc-blende structure with four-fold coordinated atoms. They have higher bonding energy and hardness, exhibit unusual electronic, mechanical, thermal, optical properties. These exclusive properties make them very useful for various technological applications including laser diodes, high efficiency photo-detectors. In this paper, we have applied the full-potential linear- augmented plane wave (FP-LAPW) method within the frame work of the density functional theory (DFT) for structural, electronic, and thermal properties calculations for Be chalcogenides. For the purpose of exchange-correlation energy (Exc) involved in Kohn–Sham calculation, the standard generalized gradient approximation (GGA) formalism has been utilized. Murnaghan's equation of state (EOS) has been used for volume optimization by minimizing the total energy with respect to the unit cell volume. With the knowledge of electronic density of states (DOS) and band structures, mechanical and thermal properties of Be chalcogenides have been estimated. The B0/G ratio for BeX chalcogenides which is greater than 1.75 is attributed to the ductile nature of the materials. An increase in positive Cauchy pressure (C12–C44), in support of strong metallic bond is observed in the range of 1.88 to 7.57 with an increase in chalcogen atomic number