Phase diagram of model anisotropic particles with octahedral symmetry

TL;DR

This study maps the phase diagram of anisotropic particles with octahedral symmetry, revealing various crystalline phases and their stability conditions based on pressure and temperature.

Contribution

It provides the first detailed phase diagram for particles with octahedral symmetry, highlighting the stability regions of different crystalline phases.

Findings

Simple cubic crystal is most stable at low pressure.

Body-centred cubic crystal forms at moderate pressures.

Face-centred cubic phases are stable at high pressures and temperatures.

Abstract

We computed the phase diagram for a system of model anisotropic particles with six attractive patches in an octahedral arrangement. We chose to study this model for a relatively narrow value of the patch width where the lowest-energy configuration of the system is a simple cubic crystal. At this value of the patch width, there is no stable vapour-liquid phase separation, and there are three other crystalline phases in addition to the simple cubic crystal that is most stable at low pressure. Firstly, at moderate pressures, it is more favourable to form a body-centred cubic crystal, which can be viewed as two interpenetrating, and almost non-interacting, simple cubic lattices.Secondly, at high pressures and low temperatures, an orientationally ordered face-centred cubic structure becomes favourable. Finally, at high temperatures a face-centred cubic plastic crystal is the most stable solid phase.