Dumbbell diffusion in a spatially periodic potential

TL;DR

This paper numerically studies how a dumbbell's Brownian motion and diffusion are affected by a two-dimensional periodic potential, revealing how potential amplitude influences diffusion and hydrodynamic interactions.

Contribution

It introduces a detailed Langevin model including hydrodynamic interactions to analyze dumbbell diffusion in periodic potentials, highlighting the effects of potential amplitude and stiffness.

Findings

Diffusion constant decreases with increasing potential amplitude.

Hydrodynamic interactions are reduced as potential amplitude increases.

Dumbbell diffusion shows a local maximum at specific wavelength related to dumbbell size.

Abstract

We present a numerical investigation of the Brownian motion and diffusion of a dumbbell in a two-dimensional periodic potential. Its dynamics is described by a Langevin model including the hydrodynamic interaction. With increasing values of the amplitude of the potential we find along the modulated spatial directions a reduction of the diffusion constant and of the impact of the hydrodynamic interaction. For modulation amplitudes of the potential in the range of the thermal energy the dumbbell diffusion exhibits a pronounced local maximum at a wavelength of about 3/2 of the dumbbell extension. This is especially emphasized for stiff springs connecting the two beads.