Phase behaviour and dynamics of three-dimensional active dumbbell systems.

Area of Science:

• Soft matter physics
• Computational physics
• Chemical physics

Background:

• Active matter systems exhibit complex behaviors driven by self-propulsion.
• Attractive interactions can significantly alter phase transitions in physical systems.
• Understanding phase diagrams is crucial for predicting material properties and dynamics.

Purpose of the Study:

• To investigate the phase behavior and dynamics of a 3D active dumbbell system with attractive interactions.
• To construct a detailed phase diagram by varying activity, density, and attraction strength.
• To identify and characterize novel phases and dynamical behaviors.

Main Methods:

• Comprehensive numerical simulations of a three-dimensional active dumbbell model.
• Systematic exploration of parameter space including activity, density, and attraction strength.
• Analytical descriptions of observed phenomena, particularly helical motion.

Main Results:

• Attractive interactions are essential for the emergence of nontrivial phases.
• Identified distinct phases: disordered, gel, and completely phase-separated.
• Discovered a novel dynamical phase: the percolating network, characterized by a spanning connected dumbbell network.
• Characterized the helical motion of dense clusters in the phase-separated regime.

Conclusions:

• The interplay of activity and attraction dictates the rich phase behavior of active dumbbell systems.
• The percolating network phase represents a new state of matter in active systems.
• Analytical and numerical findings provide a framework for understanding active matter self-organization.