Site-averaging in the integral equation theory of interaction site models of macromolecular fluids: An exact approach

TL;DR

This paper introduces an exact method for site-averaging in integral equation theories of macromolecular fluids, simplifying the mathematical framework without approximations and aiding future theoretical developments.

Contribution

It presents a novel exact approach to site-averaging that reduces the Ornstein-Zernike equations to a single equation, eliminating approximations in the process.

Findings

Exact site-averaging procedure without approximation

Reduction of multiple equations to a single Ornstein-Zernike equation

Application to rederive molecular closures

Abstract

A simple "trick" is proposed, which allows to perform exactly the site-averaging procedure required when developing integral equation theories of interaction site models of macromolecular fluids. It shows that no approximation is involved when the number of Ornstein-Zernike equations coupling the site-site correlation functions is reduced to one. Its potential practical interest for future theoretical developments is illustrated with a rederivation of the so-called molecular closures.