(437a) Adsorption of Atomic and Molecular Fluids in a Porous Material Using Expanded Wang-Landau Simulations

We propose to apply Expanded Wang-Landau simulations to study the adsorption of atomic and molecular fluids in porous materials. This approach relies on a uniform sampling of the number of atoms and molecules adsorbed. The method consists in determining a high accuracy estimate of the grand-canonical partition function for the adsorbed fluids. Then, using the formalism of statistical mechanics, we calculate absolute and excess thermodynamic properties relevant to adsorption processes. In this paper, we examine the adsorption of Argon and carbon dioxide in the isoreticular metal-organic framework IRMOF-1. We assess the reliability of the method by showing that the predicted adsorption isotherms and isosteric heats are in excellent agreement with simulation results obtained from Grand Canonical Monte Carlo simulations. We also show that the proposed method is very efficient since a single Expanded Wang-Landau simulation run at a given temperature provides the whole adsorption isotherm. Moreover, this approach provides a direct access to a wide range of thermodynamic properties, such as e.g the excess Gibbs free energy and the excess entropy of adsorption.