Thermodynamic properties of lead at high temperatures and high pressures-mean-field potential approach

In the present paper, we report theoretical calculations for the thermodynamic properties of lead (Pb) at high temperatures and pressures. We use the mean-field potential (MFP) model proposed recently by Wang and Li (Phys. Rev. B 62 (2000) 196) for evaluating the vibrational contribution of the lattice ion to the total free energy. The MFP seen by the lattice ion is constructed, for the first time, in terms of the total energy-volume relation using the local pseudopotential due to Fiolhais et al. (Phys. Rev. B 51 (1995) 14 001). We have calculated static compression, shock-wave compression, thermal expansion (βP), isothermal and adiabatic bulk moduli (BT and BS), internal energy, specific heats (CV and CP), thermodynamic Grüneisen parameter (γth), anharmonic contribution to the specific heat and temperature along shock Hugoniot. The results are satisfactorily comparable with those generated through first-principles methods, other theoretical methods and with experiments. We demonstrate that in comparison with other theoretical models, the present model has the advantages of computational simplicity and physical transparency.