Tuning nonequilibrium phase transitions with inertia.

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Active systems, unlike equilibrium systems, exhibit unique behaviors driven by internal energy sources.
• Inertia's role in active matter dynamics is often overlooked but can significantly impact system structure.
• Nonequilibrium phenomena, such as motility-induced phase separation, challenge traditional thermodynamic principles.

Purpose of the Study:

• To investigate the influence of particle inertia on the phase behavior of active systems.
• To demonstrate how increasing inertia can lead to effective equilibrium-like states in driven systems.
• To explore the underlying mechanisms and implications of inertia-induced transitions in active matter.

Main Methods:

• Simulations of active Brownian spheres with varying inertia.
• Analysis of phase separation, crystallization, and statistical properties.
• Theoretical framework to explain the conversion of active stresses to passive-like stresses.

Main Results:

• Increasing particle inertia suppresses motility-induced phase separation in active Brownian spheres.
• Higher inertia restores equilibrium crystallization, mimicking passive systems.
• Nonequilibrium patterns disappear in various driven systems with increasing inertia.
• Effective temperature becomes density-dependent, a signature of residual nonequilibrium dynamics.

Conclusions:

• Particle inertia is a crucial parameter that can drive active systems towards effective equilibrium states.
• The phenomenon offers a mechanism to tune and potentially control nonequilibrium phase transitions.
• Understanding inertia's role provides insights into the effective temperature concept in driven systems.