Equation of state of a dense boron plasma by Thomas–Fermi–Dirac–Weizsäcker molecular dynamics

Simulations consistently combining classical molecular dynamics applied to nuclei and Thomas–Fermi–Dirac–Weizsäcker theory applied to electrons are used to calculate both pressure and internal energy of a boron plasma along the isotherms T=1 and 4eV. A regularized pseudopotential must be used to represent the electron-nucleus interaction; a correction of the internal energy computed allowing for the use of this pseudopotential is proposed. Comparison with results obtained by quantum molecular dynamics shows that including the gradient correction of order 1 in the gradient expansion of the electronic free energy allows to increase the domain of validity of simulations by about 30g∕cm3 toward low densities.