Driven transport of soft Brownian particles through pore-like structures: Effective size method

TL;DR

This paper investigates how soft interactions in Brownian particles influence driven transport through pore-like structures, revealing significant effects on particle current and demonstrating the usefulness of an effective size approach based on hard sphere models.

Contribution

It introduces an effective size method to analyze softcore particle transport, bridging the gap between hardcore and soft interactions in pore transport models.

Findings

Weak softness significantly alters particle current.

Effective size based on hard sphere models helps interpret soft particle behavior.

Soft interactions enable particle crossing, affecting collective dynamics.

Abstract

Single-file transport in pore-like structures constitute an important topic for both theory and experiment. For hardcore interacting particles, a good understanding of the collective dynamics has been achieved recently. Here we study how softness in the particle interaction affects the emergent transport behavior. To this end, we investigate the driven Brownian motion of particles in a periodic potential. The particles interact via a repulsive softcore potential with a shape corresponding to a smoothed rectangular barrier. This shape allows us to elucidate effects of mutual particle penetration and particle crossing in a controlled manner. We find that even weak deviations from the hardcore case can have a strong impact on the particle current. Despite this fact, the knowledge about the transport in a corresponding hardcore system is shown to be useful to describe and interpret our findings for the softcore case. This is achieved by assigning a thermodynamic effective size to the particles based on the equilibrium density functional of hard spheres.