Continuum model for polymers with finite thickness

TL;DR

This paper develops a continuum model for thick polymers, analyzing how thickness affects tangent correlations and persistence length, revealing a richer phase diagram than traditional worm-like chain models.

Contribution

It introduces a continuum framework for thick polymers and uncovers a phase diagram with a threshold in torsional rigidity influencing correlation decay.

Findings

Persistence length scales with thickness and torsional rigidity.

Existence of a threshold torsional rigidity separating decay behaviors.

Richer phase diagram compared to worm-like chain models.

Abstract

We consider the continuum limit of a recently-introduced model for discretized thick polymers, or tubes. We address both analytically and numerically how the polymer thickness influences the decay of tangent-tangent correlations and find how the persistence length scales with the thickness and the torsional rigidity of the tube centerline. At variance with the worm-like chain model, the phase diagram that we obtain for a continuous tube is richer; in particular, for a given polymer thickness there exists a threshold value for the centerline torsional rigidity separating a simple exponential decay of the tangent-tangent correlation from an oscillatory one.