Perturbation theory with a hard dumbbell reference system. I. Application to liquid nitrogen

摘要

We present a perturbation theory of molecular fluids which uses an anisotropic reference assembly. At each orientation, the potential is divided according to the Weeksndash;Chandlerndash;Andersen (WCA) prescription into a reference potential egr;0which contains the repulsive forces and a perturbation egr;1containing the attractive forces. To compute the properties of the reference system, a second perturbation is made about a reference system consisting of equivalent hard dumbells using the analogue of the WCAhyphen;blip function theory. The thermodynamic properties of the hard dumbell system are computed from an analytic equation of state due to Boublik and Nezbeda, and the correlation functions using a method developed by the authors. The theory is applied to a twohyphen;center Lennardndash;Jones model of nitrogen at high densities and shown to predict pressures in good agreement with computer simulations.