Validity of the linear mixing rule for strongly coupled ionic fluids

Monte Carlo simulations have given a precise equation of state for the classical One Component Plasma (OCP) for point charges Z in a uniform background for both the strongly coupled fluid and crystalline phases. The corresponding MC simulations of binary ionic mixtures in a uniform background, Z(1) and Z(2) at densities n(1) and n(2) have indicated that the equation of state of the mixture is given to remarkable accuracy by the linear mixing rule. We have performed a long series of MC studies on mixtures of Z(1) = 1, Z(2) = 2, 3, and 5 to obtain the very small deviations from linear mixing. The results allow us to obtain an equation of state for mixtures of accuracy comparable to that of the OCP, and to confirm the validity of the spindle shaped phase diagram.