Dynamical density functional theory for anisotropic colloidal particles.

Area of Science:

• Colloid Science
• Soft Matter Physics
• Statistical Mechanics

Background:

• Brownian dynamics typically models simple spherical particles.
• Anisotropic particles exhibit complex translational and rotational motion.
• Confined systems introduce unique particle ordering behaviors.

Purpose of the Study:

• Generalize dynamical density functional theory (DDFT) for anisotropic particles.
• Investigate orientational ordering and relaxation in confined rod suspensions.
• Compare theoretical predictions with Brownian dynamics simulations.

Main Methods:

• Extended DDFT to include rotational Brownian motion.
• Employed mean-field approximation for density functional.
• Utilized a Gaussian-segment model for rod interactions.
• Simulated concentrated rod suspensions confined by soft walls.

Main Results:

• Observed distinct orientational ordering during wall expansion (parallel) and compression (perpendicular).
• Found non-exponential relaxation dynamics in confined rod suspensions.
• Demonstrated differing dynamics when external fields are applied or removed.
• Achieved good agreement between DDFT predictions and simulation data.

Conclusions:

• The generalized DDFT accurately describes anisotropic particle dynamics in confinement.
• Confinement and external fields significantly influence particle ordering and relaxation.
• The study provides a robust theoretical framework for complex colloidal systems.