Density functional study of XRh (X = Sc, Y, Ti and Zr) intermetallic compounds

Systematic first principle calculations have been performed to study the structural, electronic, elastic, bonding and mechanical properties of ScRh, YRh (group III), TiRh and ZrRh (group IV) with the generalized gradient approximation for exchange and correlation. Ground state properties such as lattice constant (a0), bulk modulus (B), its pressure derivative (B0) and elastic constants are calculated. The calculated values of lattice constant are in good agreement with the experimental and theoretical results. The electronic and bonding patterns of the two groups of compounds have been analysed quantitatively from band structure, Fermi surfaces and contour plots. The ‘d’ states of X (X = Sc, Y, Ti and Zr) atoms play an essential role in differentiating the bonding behaviour of these two groups of compounds. The study of charge density plots reveals that group IV intermetallics are more ionic than group III intermetallics. Poisson’s ratio (σ), Young’s moduli (E), shear moduli (GH) and the ratio of elastic anisotropy factor (A) are also estimated. Ductility for these compounds is further analysed by using Pugh’s criteria, Cauchy pressure (C12–C44) and Frantsevich rule. Amongst all these intermetallics, ZrRh is found to be most ductile due to the presence of strong metallic bonding.