Density functional study of the structural, electronic, elastic and thermodynamic properties of ACRu 3 ( A = V, Nb and Ta) compounds

Abstract

Using a density functional scheme, we have investigated for the first time the structural, electronic, elastic and thermal properties of the ideal cubic antiperovskite carbides ACRu 3 ( A = V, Nb, Ta). The computed equilibrium lattice constants are in excellent agreement with the experimental data. The electronic band structures and densities of states profiles show that the studied compounds are conductors. Analysis of atomic site projected local density of states reveals that the bonding character may be described as a mixture of covalent–ionic and, due to the d states in the vicinity of the Fermi level, metallic. Pressure dependence up to 50 GPa of the single crystal and polycrystalline elastic constants has been investigated in details. Analysis of the B/ G ratios shows that VCRu 3 is slightly brittle while NbCRu 3 and TaCRu 3 are slightly ductile. We have estimated the sound velocities in the principal directions. Through the quasi-harmonic Debye model, in which the phononic effects are taken into account, the temperature and pressure effects on the lattice constant, bulk modulus, heat capacity and Debye temperature are performed.