An improved equation of state under solar interior conditions

This paper presents a simple and efficient equation of state which can be u sed for quick and accurate computing of the thermodynamic functions of part ly ionized and weakly coupled plasmas. Based on the free energy minimizatio n method, the improvement of the equation of state includes a detailed acco unt of the physical processes of non-ideal effects consisting of electron d egeneracy, Coulomb coupling and pressure ionization. The treatment of Coulo mb coupling combines the results of the quantum exchange effect of degenera te electrons at finite temperature, N-body semi-analytic theory and the ext ended Debye-Huckel theory with hard-sphere correction. For the complicated physical processes of pressure ionization an approximate model is adopted. The nonideal corrections to equation of state are calculated under solar in terior conditions.