Closed-loop liquid-vapor equilibrium in a one-component system

TL;DR

This paper presents Monte Carlo simulations revealing a novel closed-loop liquid-vapor equilibrium in a one-component system, achieved through a two-dimensional lattice model of patchy particles, with implications for understanding phase behavior in complex fluids.

Contribution

First demonstration of closed-loop liquid-vapor equilibrium in a one-component system using a lattice model of patchy particles, exploring the role of patch distribution.

Findings

Discovery of closed-loop phase diagram topology in a one-component system

Identification of patch distribution features enabling reentrant phase behavior

Discussion on potential realization in three-dimensional models and relation to salt-induced reentrant condensation

Abstract

We report Monte Carlo simulations that show closed-loop liquid-vapor equilibrium in a pure substance. As far as we know, this is the first time that such a topology of the phase diagram has been found for one-component systems. This finding has been achieved on a two-dimensional lattice model for patchy particles that can form network fluids. We have considered related models with a slightly different patch distribution in the order to understand the features of the distribution of patches on the surface of the particles that make possible the presence of the closed-loop liquid-vapor equilibrium, and its relation with the phase diagram containing the so-called empty liquids. Finally we discuss the likelihood of finding the closed-loop liquid-vapor equilibria on related models for three dimensional models of patchy particles in the continuum, and speculate on the possible relationship between the mechanism behind the closed-loop liquid vapor equilibrium of our simple lattice model and the salt-induced reentrant condensation found in complex systems.