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In this paper, we studied the magnetic stability, structural, elastic and electronic properties of Ir2FeAl full Heusler compound in the regular phase (Cu2MnAl, prototype L2 1) , by using the first principle of density functional theory, with the generalized approximation of the GGA gradient. We found that the ferromagnetic state of Ir2FeAl is more stable than the nonmagnetic configuration at their lattice parameters equilibrium. This result was confirmed by the calculation of the cohesive energy. The stability is asserted by the elastic constants and the conditions of the mechanical stability criterion. The band structure and the calculated densities of states (DOS) of this alloy show a semi-metallic behavior. The ferromagnetic performance of Ir2FeAl is confirmed by the total magnetic moment of 4.28 μ B , where its major contribution comes from Fe atoms. We estimated the Debye temperature of Ir2FeAl from the average speed of sound. This is the first quantitative theoretical prediction of the elastic properties of the Ir2FeAl compound, and it still awaits experimental confirmation. [ABSTRACT FROM AUTHOR]

The structural, dynamical, elastic, electronic, optical, and thermodynamic properties for the Na2ZnSnS4 compound is reported using the density functional theory in the framework of the full-potential linearized augmented plane wave method within the Wu and Cohen generalized gradient and Tran–Blaha modified Becke–Johnson approaches. Calculations shows that Na2ZnSnS4 is more stable in the kesterite phase. Phonon studies indicate that this compound is dynamically stable. The elastic constants are calculated and used to confirm the mechanical stability. Moreover, our compound is thermodynamically stable and the conditions of Sn-rich/Na-poor are necessary to form a single-phase Na2ZnSnS4 crystal. The shear modulus, Young's modulus, Poisson's ratio, anisotropy factor, Lamé's constant, and Pugh indicator have also been calculated. The electronic properties shows that Na2ZnSnS4 has a direct gap (Γ–Γ) of 3.18 eV. The optical properties suggests that Na2ZnSnS4 is a good candidate for nonlinear optical applications. The thermodynamic properties such as Debye temperature, thermal expansion coefficient, heat capacities, and entropy are also estimated under temperature and pressure effects. [ABSTRACT FROM AUTHOR]