REPLICA ORNSTEIN-ZERNIKE EQUATIONS AND SIMULATIONS OF THE STRUCTURE OF A SIMPLE FLUID IN DISORDERED POROUS-MEDIA - APPLICATION TO MONOMOLECULAR ADSORPTION

A two-dimensional (2D) model for a simple fluid adsorbed in a disorder ed porous medium is investigated by means of the replica Ornstein-Zern ike (ROZ) equations with the hypernetted chain (HNC) and Percus-Yevick (PY) approximations. In addition, Monte Carlo simulations for this mo del are presented. The structural properties of adsorbed monolayer res ulting from the theory agree well with the computer simulation data. A lso we obtain the fluid compressibility from the ROZ equations and the adsorption isotherms. Besides the hard core repulsion, a long-range i nteraction between the fluid species in the form of an attractive squa re well is included. The contribution of this long-range term is consi dered using a mean-field approximation. This permits us to analyze the qualitative dependence of the behavior of the critical density and te mperature on the matrix parameters. We find that the critical temperat ure of the hard discs with a square well attraction decreases with an increasing density of the quenched component. The critical density is less sensitive to these changes.