Equation of state of fully ionized electron-ion plasmas. II. Extension to relativistic densities and to the solid phase

The analytic equation of state of nonideal Coulomb plasmas consisting of po intlike ions immersed in a polarizable electron background [G. Chabrier and A. Y. Potekhin, Phys. Rev. E 58, 4941 (1998)] is improved, and its applica bility range is considerably extended. First, the fit of the electron scree ning contribution in the free energy of the Coulomb liquid is refined at hi gh densities where the electrons are relativistic. Second, we calculate the screening contribution for the Coulomb solid (bcc and fee) and derive an a nalytic fitting expression. Third, we propose a simple approximation to the internal and free energy of the liquid one-component plasma of ions, accur ate within the numerical errors of the most recent Monte Carlo simulations. We obtain an updated value of the coupling parameter at the solid-liquid p hase transition for the one-component plasma: Gamma (m) = 175.0+/-0.4(1 sig ma).