Diffusion of active particles in a complex environment: Role of surface scattering

Area of Science:

• Physics
• Statistical Mechanics
• Soft Matter

Background:

• Self-propelled particles can avoid trapping on obstacles.
• Understanding particle transport in confined or structured environments is crucial.

Purpose of the Study:

• Investigate the impact of boundary conditions on active particle diffusion in obstacle lattices.
• Analyze how sliding versus specular reflection affects particle dynamics and diffusivity.

Main Methods:

• Utilized simulations and theoretical modeling.
• Employed a run-and-tumble particle model with derived reorientation functions.
• Developed a deterministic model to analyze lattice-guided motion.

Main Results:

• Sliding boundary conditions yield high diffusivities, even at high obstacle densities, contrasting with specular reflection.
• A run-and-tumble model accurately describes particle dynamics, with obstacle-induced tumbles.
• Fine structure in diffusivity at high densities arises from lattice guidance, particularly for pusherlike collisions.

Conclusions:

• Nonclassical surface scattering significantly impacts particle transport, introducing lattice geometry dependence at high densities.
• The study provides insights into active particle behavior in complex environments, relevant to biological systems like bacteria.