Rotational and translational diffusion in an interacting active dumbbell system.

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Active matter systems exhibit complex behaviors driven by internal energy sources.
• Self-propelled particles, like dumbbells, display unique collective dynamics and phase transitions.
• Understanding particle interactions and environmental factors is crucial for predicting active matter properties.

Purpose of the Study:

• To investigate the dynamical properties of a 2D ensemble of self-propelled dumbbells with repulsive interactions.
• To analyze translational and rotational mean-square displacements in relation to Péclet number and particle density.
• To identify and characterize different dynamical regimes and their dependence on system parameters.

Main Methods:

• Analysis of translational and rotational mean-square displacements.
• Investigation of the influence of Péclet number (Pe) and particle density (ρ).
• Focus on the homogeneous phase of the dumbbell ensemble.

Main Results:

• The four distinct translational mean-square displacement regimes of a single active dumbbell persist at finite density under specific conditions.
• The diffusion constant's ratio to its single-dumbbell value depends solely on the Péclet number.
• Rotational dynamics exhibit rich behavior with density-dependent intermediate regimes, influenced by Péclet number and density.

Conclusions:

• The Péclet number is a key parameter governing the dynamics of self-propelled dumbbells in both translational and rotational motion.
• Finite density introduces complex behaviors, including density-dependent rotational diffusion that can be enhanced or inhibited by fluctuations near phase transitions.
• The study provides insights into the collective behavior and phase transitions of active matter systems.