Comment on "Theory of high-force DNA stretching and overstretching"

TL;DR

This paper critiques and refines the discrete persistent chain model for DNA stretching, providing a more general force extension relation applicable across all parameter ranges, unifying previous models.

Contribution

It corrects and generalizes the force extension relation in the discrete persistent chain model for DNA, covering all parameter regimes.

Findings

Corrected force extension relation valid for all l values

Unifies FJC and WLC models as special cases

Reduces to Rosa et al's result at small force

Abstract

Recently Storm and Nelson [1] (Phys.Rev. E67, 51906 (2003)) introduced the discrete persistent chain model which contains both features of the freely jointed chain (FJC) and the wormlike chain (WLC) models. Equation (20) of their paper is correct only in a special case of large l, the ratio of the persistence length to the monomer length. This special case is unnecessary because the general case can be studied just as easily. Working out the general case, we obtain the force extension relation correct for all values of the parameter l. This force extension relation reduces to the FJC result at small l and to the WLC at large l. At small force, it reduces to the result of Rosa et al (cond-mat/0307015).