The finite-temperature density functional theory and the quasiharmonic approximation are adopted to investigate thermodynamics properties of hexagonal osmium. By varying lattice volume, the anharmonic effect is part considered in present work. Phonon frequencies calculations are performed from density functional perturbation theory (DFPT). By fitting the total free energy (including both electronic and vibrational parts) to equation of states at different temperatures, some classical thermodynamic quantities and their pressure and temperature d...
