Pair-distribution function of a non-polar molecular fluid based on the site-site interaction model

Abstract

The purpose of this paper is the study of the complete (i.e. orientation dependent) pair-distribution function of a diatomic molecular fluid. Using the site-site interaction model for the pair potential between molecules and the diagrammatic expansion theory, the molecular pair-distribution function (PDF) is expanded in terms of the correlation functions of a simple fluid that we refer to as reference system. Both the molecular fluid and the reference system have the same density. As a consequence the calculations will depend on the packing fraction, η, having small values, which makes the PDF converge faster. The use of a simple fluid as a reference system has an other advantage, that is the correlation functions of the simple fluid are well known.