Investigation of electronic structure and vibrational properties of the MgAuSn compund within density functional theory

Using the first-principles pseudopotential LDA approach, we have calculatedstructural and electronic properties of the cubic AlLiSi phase of MgAuSn. Thelattice constant of this material is found to be 6.39 Å, which is in a goodagrement with the experimental value of 6.41 Å.In addition to lattice constant, we have presented bulk modulus and thepressure derivative of bulk modulus of the cubic AlLiSi phase of MgAuSn. Theelectronic band structure of this material is also calculated along the highsymmetry directions. Our calculated electronic structure is also compared withrecent tight-binding linear muffin-tin orbital (TB-LMTO) results in detail. Incontrast to the experimental and theoretical works presented on the structuraland electronic properties of this material, phonons in this material has not beenstudied experimentally and theoretically yet. However, vibrational propertiesare very important for specific heats, thermal expansion, heat conduction andelectron-phonon interaction. Thus, linear response theory is used in thecalculations of the phonon dispersion curves and density of states of MgAuSn.The frequencies of zone-center phonon modes are found to be 143, 213 cm-1. Wehave also presented atomic displacement patterns of selected phonon modes atthe Γ, X and L symmetry points. From these displacement patterns, we haveobserved that the highest optical phonon mode is characterized by thevibrations of Mg atoms due to large mass differences between Mg and Au (orSn).