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Updated: Apr 25, 2026
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Forming, Confining, and Observing Microtubule-Based Active Nematics
Published on: January 13, 2023
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Absorbing phase transitions and dynamic freezing in running active matter systems
Charles Reichhardt1, Cynthia J Olson Reichhardt
1Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. cjrx@lanl.gov.
Soft Matter
|August 16, 2014
Summary
Active matter systems with randomly moving particles form transient clusters at low densities. Above a critical density, they transition to a jammed, frozen state with organized crystallites, unlike passive systems.
Area of Science:
- Physics
- Soft Matter Physics
- Statistical Mechanics
Background:
- Sterically repulsive interacting disks in 2D exhibit complex behaviors.
- Run-and-tumble dynamics models active matter with intermittent motion.
Purpose of the Study:
- Investigate the collective behavior and phase transitions in a 2D system of active disks.
- Characterize the transition from a fluctuating state to an organized, quiescent state.
Main Methods:
- Simulated a 2D system of active disks with steric repulsion.
- Analyzed system dynamics across varying densities and in the presence of pinned particles.
Main Results:
- Observed a low-density fluctuating state with transient clusters.
- Identified a critical density for transition to a drifting, quiescent/frozen state with crystallites.
- Found that active matter organizes into a dynamically jammed state, distinct from passive systems.
Conclusions:
- The transition to a frozen state is robust to fluctuations and influenced by pinned particles.
- Active matter's self-organization differs significantly from passive systems, leading to unique jammed states.
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