The ring integral in a thermodynamic perturbation theory for association

Abstract

Molecules which associate forming both inter- and intramolecular bonds have recently been considered by R.P. Sear and G. Jackson (1994, Phys. Rev. E., 50, 386) and by D. Ghonasgi and W.G. Chapman (1995, J. chem. Phys., 102, 2585). The same free energy expression was proposed in both these studies, and both considered associating chains of hard spheres, but whereas Sear and Jackson proposed a simple analytical approximation to the ring graph contribution to the free energy, Ghonasgi and Chapman evaluated it by computer simulation. The original Sear and Jackson approximation is improved and compared with the simulation data, with good agreement. It is concluded that the theory is a simple and accurate treatment of intramolecular association.