An analytical equation of state for the hard core Yukawa fluid; the electroneutral mixture

An explicit analytical equation of state is presented for an electroneutral fluid mixture of equal-sized particles which interact via hard core Yukawa potentials. Based on a perturbative scheme, analytical expressions for the coefficients of an inverse temperature expansion of internal energy in the mean-spherical approximation (MSA) are given. Extending an approximate procedure used recently for the one-component hard core Yukawa fluid, closed analytical mathematical expressions for the thermodynamics and equation of state of the electroneutral mixture are obtained. Thermodynamic properties and phase diagrams are studied for the symmetrical binary mixture. Results calculated with the analytical formulas presented here are compared with MSA results and shows excellent agreement when the interaction potential is short range. Two different binary systems are represented with the model studied in this work. In the first the interaction between particles of one species is given by repulsive Yukawa tails and the interaction between particles of different species by attractive Yukawa tails. The second system is obtained when all these forces are reversed.