Determining fluid-crystal phase boundaries for a binary hard-sphere mixture using direct-coexistence simulations

TL;DR

This paper extends a direct-coexistence simulation method to binary mixtures, enabling accurate, strain-free determination of fluid-crystal phase boundaries without prior equation of state knowledge.

Contribution

The authors adapt a recent direct-coexistence approach for monodisperse systems to binary mixtures, improving accuracy and efficiency in phase boundary determination.

Findings

Method accurately determines fluid-crystal phase boundaries in binary mixtures.

Choice of crystal plane influences the accuracy of phase boundary measurements.

The approach is simple to implement and does not need prior equation of state data.

Abstract

Determining fluid-crystal phase boundaries via direct-coexistence methods can be challenging due to the fact that the simulation box can introduce crystal strain. Recently, a direct-coexistence approach was developed which allows one to easily identify the equilibrium strain-free fluid-crystal coexistence in monodisperse systems. Here, we show that this approach can be readily extended to binary mixtures forming stoichiometric binary crystals, allowing accurate and efficient determination of the phase boundaries. Moreover, we examine how the choice of crystal plane in contact with the fluid affects the accuracy of the phase boundary determination. The method is easy to implement and does not require prior knowledge of the binary fluid's equation of state. These results further establish the method as a robust and practical tool for accurately determining fluid-crystal phase boundaries.