Barrier crossing of semiflexible polymers

TL;DR

This paper investigates the dynamics of semiflexible polymers crossing energy barriers, focusing on kink excitations, their energy, shape, and diffusion, with implications for biopolymers like DNA and actin.

Contribution

It provides a detailed analysis of kink excitations in semiflexible polymers, including their energy, shape, and diffusion, and how these influence barrier crossing behavior.

Findings

Kink motion is diffusive in symmetric potentials.

Directed kink motion occurs under external driving forces.

Barrier crossing involves nucleation and annihilation of kink-antikink pairs.

Abstract

We consider the motion of semiflexible polymers in double-well potentials. We calculate shape, energy, and effective diffusion constant of kink excitations, and in particular their dependence on the bending rigidity of the semiflexible polymer. For symmetric potentials, the kink motion is purely diffusive whereas kink motion becomes directed in the presence of a driving force on the polymer. We determine the average velocity of the semiflexible polymer based on the kink dynamics. The Kramers escape over the potential barriers proceeds by nucleation and diffusive motion of kink-antikink pairs, the relaxation to the straight configuration by annihilation of kink-antikink pairs. Our results apply to the activated motion of biopolymers such as DNA and actin filaments or synthetic polyelectrolytes on structured substrates.