We use the Rosenfeld-Ashcroft procedure of modeling the bridge function in the reference—hypernetted-chain integral equation with its hard-sphere values, and choose the sphere diameter so that the free energy of the system is minimized. The resulting integral equation is solved for both the long-range Coulomb potential and the short-range Lennard-Jones potential. The results are in excellent agreement with Monte Carlo data for the thermodynamics and structure of both systems. The method provides an entirely first-principles approach to the theory of the structure and thermodynamics of simple classical liquids.

• Received 11 April 1983

DOI:https://doi.org/10.1103/PhysRevA.28.2374