Abstract. The results of analytical approximations and extensive calculations based on a path integral Monte Carlo (PIMC) scheme are presented. A new (direct) PIMC method allows for a correct determination of thermodynamic properties such as energy and equation of state of dense degenerate Coulomb systems. In this paper, we present results for dense partially ionized hydrogen at intermediate and high temperature. We give a quantitative comparison with the available results of alternative (restricted) PIMC simulations and with analytical expressions based on iterpolation formulas meeting the exact limits at low and high densities. Good agreement between the two simulations is found up to densities of the order of 1024 cm−3 . The agreement with the analytical results is satisfactory up to densities in the range 1022 . . . 1023 cm−3 .
V. Filinov, M. Bonitz, D. Kremp, W.-D. Kraeft, V.