Structural and elastic properties of Mg_(3)CuH_(0.6)ternary hydride by ab initio study

In the present work,we investigate the structural and elastic properties of a new intermetallic hydride compound Mg 3 CuH 0.6.The theoretical study has been carried out based on density functional theory(DFT),within local density approximation(LDA)and generalized gradient approximation(GGA).The calculated structural parameters of Mg 3 CuH 0.6 compound are consistent with the available experimental data in both approximations.The heat of formation found shows that this compound has a stable structure.According to Hooke’s law which leads to a linear relation between stress and strain,the elastic constants were determined.Once the elastic constants are obtained,the bulk modulus B,shear modulus G,Young’s modulus E,Poisson’s ratioσ,for Mg 3 CuH 0.6 compound were deduced using Voigt-Reuss-Hill(VRH)approximation.The results show that this alloy exhibit ductile property.Finally,the Debye temperature is also calculated and discussed for the first time.This will be considered as the first quantitative theoretical prediction of these properties.