A new equation of state for associating Lennard–Jones fluids with two sites: small bond angle

ABSTRACT

We developed a new equation of state for Lennard–Jones spheres with two short-ranged, directional association sites. The theory is novel in that association is dependent on bond angle between the two sites, and formation of self-assembled linear and cyclic clusters is predicted in the model. The competition between ring and chain formations at various densities and temperatures is predicted by the theory and verified by Monte Carlo simulations. It was found that closed-loop structures become important at low temperatures and densities. Also, at fixed association energy, intensifying the Lennard–Jones energy reduces the extent of association in the fluid. The theory and simulation are in excellent agreement.

KEYWORDS:

• Thermodynamics
• Lennard–Jones fluid
• association
• bond angle

Acknowledgments

We gratefully acknowledge the financial support of The Robert A. Welch Foundation [grant number C-1241].

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Welch Foundation [grant number C-1241].