Thermodynamic Properties of Sodium: A First-Principles Study

The Thermal expansion, Hugoniot state and 300 K isotherm of sodium have been calculated on the basis of: (i) the accurate calculations of 0 K total energies with the full-potential linearized augmented plane wave method within the generalized gradient approximation to exchange-correlational functional and (ii) the newly developed classical mean-field statistics where both the cold and thermal parts of the Helmholtz free-energy are entirely derived from the 0 K total energy. A quite satisfactory agreement between calculation and experiment has been observed. Our approach does not invoke any empirical parameter, which has long been a desirability on the field of material science.