NEW INTEGRAL-EQUATION FOR SIMPLE FLUIDS

We present a new integral equation for the radial distribution functio n of classical fluids. It employs the bridge function for a short-rang e repulsive reference system which was used earlier in our dense fluid perturbation theory. The bridge function is evaluated using Ballone e t al.'s closure relation. Applications of the integral equation to the Lennard-Jones and inverse nth-power (n=12, 9, 6, and 4) repulsive sys tems show that it can predict thermodynamic and structural properties in close agreement with results from computer simulations and the refe rence-hypernetted-chain equation. We also discuss thermodynamic consis tency tests on the new equation and comparisons with the integral equa tions of Rogers and Young and of Zerah and Hansen. The present equatio n has no parameter to adjust. This unique feature offers a significant advantage as it eliminates a time-consuming search to optimize such p arameters appearing in other theories. It permits practical applicatio ns needing complex intermolecular potentials and for multicomponent sy stems. (C) 1995 American Institute of Physics.