Coulomb interactions for the Free Helmholtz energy and the pressure are studied in a partial new formulation which described more exactly the numerical evaluation of many body theories.
With regard to the EOS many activities have been developed to yield results which consider different phenomena, for instance pressure dissoziation and ionisation, degeneracy, relativity, Coulomb- and non-Coulombic interactions, pair production and charge mixing in different chemical compositions.
Various theoretical approaches are used in order to include exchange and correlation effects for fully ionized or partially ionized matter (see e.g. Salpeter and Zapolski 1967, Graboske et al. 1969, Hansen 1973, Pokrant 1977, Fontaine et al. 1977, March and Tosi 1984, Perrot and Dharmawardana 1984, Hubbard and Dewitt 1985, Dandrea et al. 1986, van Horn 1987, Kraeft et al. 1986, Ichimaru et al. 1987, Rogers and DeWitt 1987, Däppen et al. 1988, Ichimaru 1990, Eliezer and Ricci 1991, Saumon and Chabrier 1992).
For many applications (e.g. stellar evolution calculations or astroseismology) it is necessary either to have algebraic formulae for the EOS or extensive tables which supply the input, informations at any density and temperature. As a, first step we present an analytical EOS for fully ionized multicomponent plasmas covering a large density-temperature range. The EOS includes non-ideal effects due to exchange-correlation interactions of charged particles at any degeneracy and is applicable to any chemical mixture. Relativistic effects as well as ionic quantum corrections are taken into account.