Square-well mixtures: a study of their coexistence using theory and simulation

Abstract

We study coexistence and thermodynamic properties of square-well monomeric mixtures using both continuum integral equation theory and Monte Carlo simulation. We focus most of our attention on a mixture which is slightly asymmetric, both in terms of size and energetics, and explore the liquid-vapour coexistence behaviour for both the pure components, and selected phase envelopes in the mixture. We find the theory to be in semi-quantitative agreement with the simulation results and expect to make use of the tools developed here as we move towards studies of chain mixtures.

Keywords:

• Continuum integral equation theory
• Monomer-monomer pair distributions
• Liquid-vapour coexistence
• Square-well fluid mixtures
• Monte Carlo simulation

Acknowledgements

We would like to thank Professor Robert S. Cantor for very helpful discussions. We also thank Dartmouth Computing Services for use of the Discovery cluster. We gratefully acknowledge financial support by the National Science Foundation (Grant No. DMR-0502196), and partial support by the Donors of the American Chemical Society Petroleum Research Fund.