Ab-initio probe into the elastic, mechanical and thermo-mechanical properties of CsSe binary compound

Abstract

First principles computational simulations were performed using Quantum ESPRESSO package within the framework of Density Functional Theory (DFT) in order to analyze the structural, elastic and thermo-mechanical conditions of one of the Caesium monochalcogenides (CsSe) in a bid to fill some of the theoretical information gaps in this material. The obtained optimized lattice parameter of 7.432[Formula: see text]Å from well convergence tests agreed reasonably with results from other previous theoretical works. Three independent elastic constants ([Formula: see text], [Formula: see text] and [Formula: see text]) and other mechanical indices for this cubic system were determined by fitting stress–stain relationship data via Voigt–Reuss–Hill approximation (VRHA) of Quantum ESPRESSO incorporated Thermo_pw code. CsSe is elastically and mechanically stable since the elastic constants fulfilled the Born–Huang cubic mechanical stability criteria of forms: [Formula: see text]; [Formula: see text] and [Formula: see text]. The resistiveness of CsSe to recoverable deformation under applied force was studied via elastic moduli: bulk (B), Young (E) and shear (G) moduli. Pugh’s ratio ([Formula: see text]) [Formula: see text] depicted ductility and the positive value of Cauchy pressure: [Formula: see text][Formula: see text]GPa further confirmed the ductile nature of this system. Poisson ratio, [Formula: see text], within the domain of 0.25 and 0.42, classified the compound as a metallic bonded specie. One of the three estimated sound velocity variants for the system best predicted the average Debye temperature. Some other important structural and thermo-mechanical-related parameters such as Zener anisotropy, elastic constants based Debye temperature, average speed of sound, Lame’s constants, Kleinmann parameters, hardness (micro and macro) and melting temperature were determined. The interdependencies of these obtained parameters were established and reported.