Analytic solutions for Baxter's model of sticky hard sphere fluids within closures different from the Percus_Yevick approximation

摘要

We discuss structural and thermodynamical properties of Baxter's adhesivehard sphere model within a class of closures which includes the Percus-Yevick(PY) one. The common feature of all these closures is to have a directcorrelation function vanishing beyond a certain range, each closure beingidentified by a different approximation within the original square-well region.This allows a common analytical solution of the Ornstein-Zernike integralequation, with the cavity function playing a privileged role. A carefulanalytical treatment of the equation of state is reported. Numerical comparisonwith Monte Carlo simulations shows that the PY approximation lies betweensimpler closures, which may yield less accurate predictions but are easilyextensible to multi-component fluids, and more sophisticate closures which givemore precise predictions but can hardly be extended to mixtures. In regimestypical for colloidal and protein solutions, however, it is found that theperturbative closures, even when limited to first-order, produce satisfactoryresults.