Generalized van der Waals theory. V. Equation of state of two-dimensional simple fluid

Abstract

We have investigated the two-dimensional gas-liquid condensation of a LJ(12-6) system with relevance to monolayer adsorption. A recently developed generalized van der Waals theory has been used to calculate critical parameters, coexistence curves, vapour pressure curves and other thermodynamic information partially as an investigation into the validity of the theory. Two aspects are of particular concern. Firstly, we are interested in the temperature and density dependence of the excluded volume effect. The effective hard-disc diameter is determined variationally so as to minimize the free energy. Secondly, we apply a simple means of quantizing the theory to estimate shifts in the thermodynamic properties of light fluids due to the quantum character of the translational motion. Apparently useful accuracy is obtained.