Lattice dynamics and elastic properties of Mg3As2 and Mg3Sb2 compounds from first-principles calculations

We investigated the structure, elastic properties, lattice dynamics, and a few of the thermodynamic properties of beta-Mg3As2 and alpha-Mg3Sb2 compounds with anti-La2O3 structure using first-principles calculations based on density-functional theory. The fully relaxed structure parameters of Mg3As2 and Mg3Sb2 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 Gamma point of the Brillouin zone. Thermodynamic quantities such as vibrational entropy, constant-volume specific heat, and Debye temperature are also presented. (C) 2010 Elsevier B.V. All rights reserved.