Theoretical study of elastic, mechanical and thermodynamic properties of MgRh intermetallic compound

In the last years,Magnesium alloys are known to be of great technological importance and high scientific interest.In this work,density functional theory plane-wave pseudo potential method,with local density approximation(LDA)and generalized gradient approximation(GGA)are used to perform first-principles quantum mechanics calculations in order to investigate the structural,elastic and mechanical properties of the intermetallic compound MgRh with a CsCl-type structure.Comparison of the calculated equilibrium lattice constant and experimental data shows good agreement.The elastic constants were determined from a linear fit of the calculated stress-strain function according to Hooke's law.From the elastic constants,the bulk modulus B,shear modulus G,Young's modulus E,Poisson's ratioσ,anisotropy factor A and the ratio B/G for MgRh compound are obtained.The sound velocities and Debye temperature are also predicted from elastic constants.Finally,the linear response method has been used to calculate the thermodynamic properties.The temperature dependence of the enthalpy H,free energy F,entropy S,and heat capacity at constant volume C_(v)of MgRh crystal in a quasi-harmonic approximation have been obtained from phonon density of states and discussed for the first report.This is the first quantitative theoretical prediction of these properties.

Density functional study of elastic,mechanical and thermodynamic properties of MgCu with a CsCl-type structure

We have employed the density functional theory plane-wave pseudo potential method,with local density approximation and generalized gradient approximation to perform first-principles quantum mechanics calculations in order to investigate the structural,elastic and mechanical properties of the intermetallic compound MgCu with a CsCl-type structure.The calculated equilibrium lattice constant is in good agreement with the experimental and theoretical values.The elastic constants were determined from a linear fit of the calculated stress-strain function according to Hooke’s law.From the elastic constants,the bulk modulus B,anisotropy factor A,shear modulus G,Young’s modulus E,Poisson’s ratio y,and the ratio B/G for MgCu compound are obtained.Our calculated results for the bulk modulus B,and Young’s modulus E are consistent with the experimental and theoretical data.The sound velocities and Debye temperature are also predicted from elastic constants.Finally,the linear response method has been used to calculate the thermodynamic properties.The temperature dependence of the enthalpy H,free energy F,entropy S,and heat capacity at constant volume Cv of MgCu crystal in a quasi-harmonic approximation have been obtained from phonon density of states and discussed for the first report.

Elastic and mechanical properties of Mg3Rh intermetallic compound:An ab initio study

In this work, density functional theory plane-wave pseudo potential method, with local density approximation (LDA) and generalized gradientapproximation (GGA) are used to investigate the structural, elastic, mechanical and thermodynamic properties of the intermetallic compoundMg3Rh. Comparison of the calculated equilibrium lattice constants and experimental data shows very good agreement. The elastic constants weredetermined from a linear fit of the calculated stress-strain function according to Hooke’s law. From the elastic constants, the bulk modulus B, shearmodulus G, Young’s modulus E, Poisson’s ratio σ, anisotropy factor A, the ratio B/G and the hardness parameter H for Mg3Rh compound areobtained. Our calculated elastic constants indicate that the ground state structure of Mg3Rh is mechanically stable. The calculation results showthat this intermetallic crystal is stiff, elastically anisotropic and ductile material. The sound velocities and Debye temperature are also predictedfrom elastic constants. This is the first quantitative theoretical prediction of these properties.