Lattice dynamics and elastic properties of Mg 3As 2 and Mg 3Sb 2 compounds from first-principles calculations

Abstract

We investigated the structure, elastic properties, lattice dynamics, and a few of the thermodynamic properties of β-Mg 3As 2 and α-Mg 3Sb 2 compounds with anti-La 2O 3 structure using first-principles calculations based on density-functional theory. The fully relaxed structure parameters of Mg 3As 2 and Mg 3Sb 2 compounds are in good agreement with previous experimental results. The linear response method is applied to determine the phonon dispersion relations, phonon density of states, Born effective charge, and optical phonon frequencies at the Γ point of the Brillouin zone. Thermodynamic quantities such as vibrational entropy, constant-volume specific heat, and Debye temperature are also presented.