Structural and elastic properties under pressure effect of the cubic antiperovskite compounds ANCa3 (A = P, As, Sb, and Bi)

Using first-principles density functional calculations, the effect of high pressures, up to 40 GPa, on the structural and elastic properties of ANCa3, with A = P, As, Sb, and Bi, were studied by means of the pseudo-potential plane-waves method. Calculations were performed within the local density approximation and the generalized gradient approximation for exchange-correlation effects. The lattice constants are in good agreement with the available results. The elastic constants and their pressure dependence are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young's modulus, Poisson's ratio and Lamé's constants for ideal polycrystalline ANCa3 aggregates. By analysing the ratio between the bulk and shear moduli, we conclude that ANCa3 compounds are brittle in nature. We estimated the Debye temperature of ANCa3 from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of PNCa3, AsNCa3, SbNCa3, and BiNCa3 compounds, and it still awaits experimental confirmation.