A model for the structure of square-well fluids

Abstract

A simple explicit expression for the Laplace transform of rg(r) for 3D square-well fluids is proposed. The model is constructed by imposing the following three basic physical requirements: (a) lim r→σ+g(r) = finite, (b) limq→0S(q) = finite, and (c) limr→σ-g(r)/lim r→λ+g(r) = exp(ε|kBT). When applied to ID square-well fluids, the model yields the exact radial distribution function. Furthermore, in the sticky-hard-sphere limit [λ→1, ε→∞, (λ.-1)exp(ε/kBT)=finite] the model reduces to Baxter's exact solution of the Percus-Yevick equation. Comparison with Monte Carlo simulation data shows that the model is a good extension of Baxter's solution to "thin" square-well fluids. For "wide" square-well fluids the model is still an acceptable approximation even for densities slightly above the critical density and temperatures slightly below the critical temperature. © 1994 American Institute of Physics.