Soft Spheres Make More Mesophases

TL;DR

This study combines mean-field and simulation methods to explore how particles with hard-core and soft shoulder interactions form diverse phases, revealing universal features and aggregation behaviors driven by competing length scales.

Contribution

It introduces a comprehensive analysis of phase behavior in particles with purely repulsive interactions, highlighting universal features and aggregation mechanisms.

Findings

Multiple aggregate phases observed despite repulsive interactions

Universal phase diagram features at large shoulder widths

Constant inter-aggregate separation maintained across phases

Abstract

We use both mean-field methods and numerical simulation to study the phase diagram of classical particles interacting with a hard-core and repulsive, soft shoulder. Despite the purely repulsive interaction, this system displays a remarkable array of aggregate phases arising from the competition between the hard-core and shoulder length scales. In the limit of large shoulder width to core size, we argue that this phase diagram has a number of universal features, and classify the set of repulsive shoulders that lead to aggregation at high density. Surprisingly, the phase sequence and aggregate size adjusts so as to keep almost constant inter-aggregate separation.