Local interactions in active matter are reinforced by spatial structure

Area of Science:

• Complex Systems
• Statistical Physics
• Collective Behavior

Background:

• The Vicsek model is a standard for studying self-propelled particle flocking.
• Previous studies explored interaction rules, speed, and obstacle density.
• The impact of interaction radius on flocking in heterogeneous environments is not well understood.

Purpose of the Study:

• Investigate the effect of interaction radius on Vicsek particle flocking in environments with obstacles.
• Analyze how obstacles influence group density and collective behavior phases.
• Determine if obstacles can facilitate global order despite increased noise.

Main Methods:

• Simulations of the Vicsek model in heterogeneous environments.
• Systematic variation of interaction radius and noise levels.
• Analysis of flocking polarization, group density, and phase transitions.

Main Results:

• Interaction radius significantly affects flock alignment and realignment after obstacle collisions.
• Obstacles alter group density, enabling the identification of distinct collective behavior phases.
• Counter-intuitively, obstacles can promote global order as system noise increases.

Conclusions:

• The scale of particle perception (interaction radius) is crucial in heterogeneous environments.
• Obstacles can paradoxically enhance flocking order by influencing group density and enabling new collective behaviors.
• This finding has implications for designing artificial systems and understanding natural flocking.