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

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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.