Theory of Nonequilibrium Crystallization and the Phase Diagram of Active Brownian Spheres

Fuente: arXiv
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Autores principales: Evans, Daniel, Omar, Ahmad K.
Formato: Preprint
Publicado: 2024
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author Evans, Daniel
Omar, Ahmad K.
author_facet Evans, Daniel
Omar, Ahmad K.
contents The crystallization of hard spheres at equilibrium is perhaps the most familiar example of an entropically-driven phase transition. In recent years, it has become clear that activity can dramatically alter this order-disorder transition in unexpected ways. The theoretical description of active crystallization has remained elusive as the traditional thermodynamic arguments that shape our understanding of passive freezing are inapplicable to active systems. Here, we develop a statistical mechanical description of the one-body density field and a nonconserved order parameter field that represents local crystalline order. We develop equations of state, guided by computer simulations, describing the crystallinity field which result in shifting the order-disorder transition to higher packing fractions with increasing activity. We then leverage our recent dynamical theory of coexistence to construct the full phase diagram of active Brownian spheres, quantitatively recapitulating both the solid-fluid and liquid-gas coexistence curves and the solid-liquid-gas triple point.
format Preprint
id arxiv_https___arxiv_org_abs_2411_14536
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Theory of Nonequilibrium Crystallization and the Phase Diagram of Active Brownian Spheres
Evans, Daniel
Omar, Ahmad K.
Statistical Mechanics
Soft Condensed Matter
The crystallization of hard spheres at equilibrium is perhaps the most familiar example of an entropically-driven phase transition. In recent years, it has become clear that activity can dramatically alter this order-disorder transition in unexpected ways. The theoretical description of active crystallization has remained elusive as the traditional thermodynamic arguments that shape our understanding of passive freezing are inapplicable to active systems. Here, we develop a statistical mechanical description of the one-body density field and a nonconserved order parameter field that represents local crystalline order. We develop equations of state, guided by computer simulations, describing the crystallinity field which result in shifting the order-disorder transition to higher packing fractions with increasing activity. We then leverage our recent dynamical theory of coexistence to construct the full phase diagram of active Brownian spheres, quantitatively recapitulating both the solid-fluid and liquid-gas coexistence curves and the solid-liquid-gas triple point.
title Theory of Nonequilibrium Crystallization and the Phase Diagram of Active Brownian Spheres
topic Statistical Mechanics
Soft Condensed Matter
url https://arxiv.org/abs/2411.14536