First-principle calculations to investigate the elastic and thermodynamic properties of RBRh3 (R = Sc, Y and La) perovskite compounds

We have performed first-principle calculations using the full-potential linear augmented plane wave (FP-LAPW) method within density functional theory (DFT) to investigate the structural, elastic and thermodynamic properties of the cubic perovskite RBRh3 (R = Sc, Y and La) compounds. The exchange-correlation potential is treated within the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE). Single-crystal elastic constants are calculated using the total energy variation versus strain technique, then the shear modulus, Young's modulus, Poisson's ratio and anisotropic factor are derived for polycrystalline RBRh3 using the Voigt-Reuss-Hill approximations. Analysis of the calculated elastic constants C-ij and B/G ratios shows that these compounds are mechanically stable and ductile in nature. Using the quasi-harmonic Debye model, the effect of pressure P and temperature T on the lattice parameter a(0), bulk modulus B-0, thermal expansion coefficient alpha, Debye temperature theta(D) and the heat capacity C-v for these compounds are investigated for the first time. The computed structural and elastic constants are in good agreement with the available experimental and theoretical data.