Lennard-Jones Mixtures in a Cylindrical Pore. A Comparison of Simulation and Density Functional Theory

Abstract

We report simulation results for binary Lennard-Jones mixtures in narrow cylindrical pores. The parameters are chosen to model an Ar-Kr mixture in a carbon dioxide pore. We focus on capillary condensation and locate this transition directly via a molecular dynamics simulation of two-phase coexistence. The chemical potentials in the pore are obtained via the particle insertion method. The latter results are used in a subsequent grand canonical Monte Carlo simulation in order to determine the bulk pressure, density and composition. We report density profiles and phase diagrams and compare the results with the local version of mean field density functional theory predictions for the same model. The simulation results for a mixture in which we neglect the size difference between Ar and Kr are compared with the non-local theory.

Key Words:

• Lennard-Jones mixture
• cylindrical pores
• molecular dynamics
• mean field theory