A theory for the structure and thermodynamics of molten Li/K Cl

We use an improved hypernetted chain (IHNC) approximation to calculate the total correlation functions hλν and some thermodynamic properties of the binary alkali halide Li/K Cl over the whole concentration range. The pair interactions are assumed to be of the Born–Huggins–Mayer form. The bridge functions incorporated in our scheme and neglected in ordinary HNC calculations are based on the first diagram of their hξ1ξ2-bond, density expansions. Comparison with simulation data shows that certain severe structural defects of the HNC results are removed by our procedure. We find semiquantitative agreement with experimental estimates for the long-wavelength limits of the partial structure factors which are connected to the mixing thermodynamics of the system. This is a significant improvement over the HNC approximation which yields a qualitatively wrong concentration dependence of these quantities. The significance of thermodynamic self-consistency is demonstrated.