All-electron study of ultra-incompressible superhard material ReB2: structural and electronic properties

This paper investigates the structural and electronic properties of rhenium diboride by first-principles calculation based on density functional theory. The obtained results show that the calculated equilibrium structural parameters of ReB₂ are in excellent agreement with experimental values. The calculated bulk modulus is 361~GPa in comparison with that of the experiment. The compressibility of ReB₂ is lower than that of well-known OsB₂. The anisotropy of the bulk modulus is confirmed by c/a ratio as a function of pressure curve and the bulk modulus along different axes along with the electron density distribution. The high bulk modulus is attributed to the strong covalent bond between Re-d and B-p orbitals and the wider pseudogap near the Fermi level, which could be deduced from both electron charge density distribution and density of states. The band structure and density of states of ReB₂ exhibit that this material presents metallic behavior. The good metallicity and ultra-incompressibility of ReB₂ might suggest its potential application as pressure-proof conductors.