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Stationary broken parity states in active matter models
Tobias Frohoff-Hülsmann1, Max Philipp Holl1, Edgar Knobloch2
1Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany.
Physical Review. E
|July 19, 2023
Summary
Several active matter models show unexpected stationary states due to a spurious gradient structure. Correcting this structure leads to generic behavior with moving states, crucial for understanding active systems.
Area of Science:
- Physics
- Complex Systems
- Nonlinear Dynamics
Background:
- Active matter and active systems are crucial in diverse fields.
- Nonvariational continuum models are widely used to describe these systems.
- Understanding localized states and their dynamics is key to active matter physics.
Purpose of the Study:
- To identify and explain nongeneric behavior in common active matter models.
- To investigate the origin of spurious stationary localized states.
- To determine modifications for achieving generic behavior in active systems.
Main Methods:
- Analysis of nonvariational continuum models for active matter.
- Identification of a "spurious" gradient dynamics structure.
- Numerical continuation of resting and drifting localized states.
- Bifurcation analysis (drift-transcritical and drift-pitchfork).
Main Results:
- Nonvariational models exhibit asymmetric, stationary localized states without pinning.
- These states appear via drift-transcritical bifurcations as activity increases.
- A spurious gradient dynamics structure was identified as the cause.
- Generic models with added terms show asymmetric states appearing via drift-pitchfork bifurcations, leading to moving states.
Conclusions:
- Common nonvariational models for active matter display nongeneric behavior.
- The presence of stationary localized states in active systems is an artifact of model structure.
- Modifications to model dynamics are necessary to achieve generic behavior and accurately describe active system dynamics.
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