Lattice dynamics of Mg2Si and Mg2Ge compounds from first-principles calculations

We report first-principles calculations of the structure, elastic properties, lattice dynamics and some thermodynamic properties of Mg2Si and Mg2Ge compounds. The fully relaxed structure parameters and elastic stiffness constants of Mg2Si and Mg2Ge compounds are in good agreement with previous experimental data. The linear response method is applied to determine the phonon dispersion relations, phonon density of states, and Born effective charge. The computed thermodynamic properties such as vibrational entropy, constant-volume specific heat, and Debye temperature coincide with previous experimental data. (C) 2007 Elsevier B.V. All rights reserved.