A FP-LAPW study of RAl3 (R = Yb, Lu and Sc) compounds
Veena Thakur and Gitanjali Pagare
The structural, electronic, elastic, mechanical and thermal properties of isostructural and isoelectronic nonmagnetic RAl3 (R = Yb, Lu and Sc) compounds, which crystallize in AuCu3-type structure, are studied using first principles density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The calculations are carried out within PBE-GGA, WC-GGA and PBE-sol GGA for the exchange correlation potential. Our calculated ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B′) are in good agreement with the available experimental and other theoretical results. We predict the elastic constants for these compounds using GGA approximations. All the compounds are found to be brittle in nature in accordance with Pugh’s criteria. The computed electronic band structures and density of states show metallic character of these compounds. The elastic properties including Poisson’s ratio (σ), Young’s modulus (E), shear modulus (GH) and anisotropy factor (A) are also determined using the Voigt-Reuss-Hill (VRH) averaging scheme. The average sound velocities (𝒱m), density (ρ) and Debye temperature (θD) of these RAl3 compounds are also estimated from the elastic constants. We first time report the variation of elastic constants, elastic moduli, sound velocities and Debye temperatures of these compounds as a function of pressure.
Keywords: Density functional theory, exchange correlation potential, electronic structure, density of states, pugh’s criteria, Debye’s temperature