A radially accurate perturbation theory for molecular liquids such as nitrogen or fluorine

Abstract

We derive a molecular perturbation theory that accurately predicts the centers distribution function for Lennard‐Jones diatomic models of N2 and F2 at their triple points. The motivation for this work stems from a pre‐existing need in molecular perturbation theory for a theory that would generate accurate values of this function. For N2, the predicted values of this function are essentially quantitative and for F2 they are nearly so. The theory is physically based and contains no adjustable parameters. The derivation is based on a first‐order functional Taylor expansion of the background pair correlation function y(12). The expansion functional is selected so as to cause the numbers of nearest neighbors in the isotropic reference fluid and the molecular fluid to be the same. We also report other measures of structures and thermodynamics, and we make comparisons with related theories.