First-principles study of structural and thermodynamic properties of osmium

We employ the first-principles plane wave pseudopotential density functional theory method to calculate the equilibrium lattice parameters of osmium and the thermodynamic properties of hcp structure osmium. The obtained lattice parameters are in good agreement with the experimental data investigated up to 58.2 GPa using radial X-ray diffraction (RXRD) together with lattice strain theory in a diamond-anvil cell and the available theoretical data of others. Through the quasi-harmonic Debye model, the dependencies of the normalized lattice parameters a/a(0) and c/c(0) on pressure P, the normalized primitive volume V/V-0 on pressure P, the Debye temperature Theta(D) and the heat capacity C-V on pressure P and temperature T, as well as the variation of the thermal expansion alpha with temperature and pressure are obtained successfully. (C) 2011 Elsevier B.V. All rights reserved.