Mechanical coupling in flashing ratchets

TL;DR

This paper investigates how rigid, chain-like objects move in a flashing ratchet potential, revealing that their velocity can reverse multiple times due to size and temperature effects, with implications for modeling molecular motors.

Contribution

It introduces analytical and simulation analysis of coupled objects in ratchet potentials, highlighting size and temperature effects on transport direction.

Findings

Velocity reversals depend on chain size and temperature.

Effective potential symmetry differs from individual particles.

Analytical results confirmed by Brownian dynamics simulations.

Abstract

We consider the transport of rigid objects with internal structure in a flashing ratchet potential by investigating the overdamped behavior of a rod-like chain of evenly spaced point particles. In 1D, analytical arguments show that the velocity can reverse direction multiple times in response to changing the size of the chain or the temperature of the heat bath. The physical reason is that the effective potential experienced by the mechanically coupled objects can have a different symmetry than that of individual objects. All analytical predictions are confirmed by Brownian dynamics simulations. These results may provide a route to simple, coarse-grained models of molecular motor transport that incorporate an object's size and rotational degrees of freedom into the mechanism of transport.