Intermediate scattering function of an anisotropic active Brownian particle.

Area of Science:

• Physics
• Biophysics
• Soft Matter Physics

Background:

• Active agents like bacteria exhibit complex motion in fluids.
• Low Reynolds number hydrodynamics presents unique challenges for autonomous movement.
• Stochastic fluctuations significantly impact directed motion.

Purpose of the Study:

• To derive analytically exact expressions for the intermediate scattering function of a single, anisotropic active Brownian particle.
• To characterize the spatio-temporal dynamics of active agents in 3D.
• To provide a theoretical framework for interpreting scattering experiments of active matter.

Main Methods:

• Mesoscopic modeling of a single anisotropic active Brownian particle.
• Analytical derivation of the intermediate scattering function.
• Calculation of mean-square displacement and non-Gaussian parameter from the scattering function.

Main Results:

• Exact expressions for the intermediate scattering function were obtained.
• Oscillatory behavior in the scattering function at intermediate wavenumbers indicates persistent swimming.
• Different temporal regimes show bare translational diffusion, directed motion, and enhanced effective diffusion.

Conclusions:

• The derived intermediate scattering function provides a comprehensive characterization of active particle motion.
• The study rationalizes the interplay between translational and rotational diffusion.
• This work serves as a reference for future studies on active matter and experimental observations.