Local structure of fluids containing chain-like molecules: Polymer reference interaction site model with a Yukawa closure

Abstract

The local structure of fluids composed of chain-like molecules (modeled as a pearl necklace of freely jointed hard spheres) is investigated via an integral equation approach. A Yukawa closure for the direct correlation function is used in the framework of polymer-RISM theory. This introduces two free parameters which are chosen by matching the theory's predictions for the compressibility and the contact value of the site-site distribution function, to an equation of state and simulation data, respectively. The theory shows good agreement when compared to Monte Carlo simulations of tangent diatomics, and freely jointed 4-mers, and 8-mers. Methods for estimating the contact value of the site-site distribution function are discussed. © 1990 American Institute of Physics.