Pressure and temperature dependent ab-initio quasi-harmonic thermoelastic properties of tungsten

In this presentation we show the ab-initio temperature and pressure dependent thermoelastic properties of body-centered cubic tungsten. The temperature dependent quasi-harmonic elastic constants are computed at several reference volumes and interpolated at different temperatures and pressures. Our results are compared with room pressure experimental elastic constants on a single crystal and with the recent measurements of the pressure and temperature dependent compressional and shear sound velocities of polycrystalline tungsten, finding a reasonable agreement. Moreover, we present the phonon dispersions, the thermal pressure-volume equations of state, and the temperature dependent volumetric thermal expansion, isobaric heat capacity, adiabatic bulk modulus, and average Gr"uneisen parameter at ambient and high pressures. All these quantities are computed with three exchange and correlation functionals: LDA, PBE, and PBEsol. The differences among functionals decrease with pressure and the ab-initio results are in agreement with empirical high pressure extrapolations of the experimental data.