Relating monomer to center-of-mass distribution functions in macromolecular fluids: extension to arbitrary systems

In the framework of the polymer reference interaction site model (PRISM) extended to incorporate the centers of mass (CM) of the groups of monomers constitutive of the macromolecules as auxiliary sites, a general relationship between the monomer-monomer and CM-CM pair correlation functions is derived for arbitrary mixtures of macromolecules of arbitrary structure. It extends previous results for homopolymer fluids and should be useful to develop semi-analytic coarse-grained descriptions of complex fluids.