Kinetic Pathways of the DNA Melting Transition

TL;DR

This paper explores the kinetic pathways of DNA melting using extended models, revealing how increased interaction range leads to diffuse nucleating droplets near pseudospinodals, contrasting classical nucleation predictions.

Contribution

It introduces a phi^4-field theory for the PS model and a mean field approach for the PDB model to analyze DNA melting kinetics and nucleation behavior.

Findings

Increased interaction range leads to pseudospinodal proximity.

Nucleating droplets become diffuse near pseudospinodal.

Results contrast with classical nucleation theory predictions.

Abstract

We investigate kinetic pathways of the DNA melting transition using variable-range versions of the Poland-Scheraga (PS) and Peyrard-Dauxois-Bishop (PDB) models of DNA. In the PS model, we construct a phi^4-field theory to calculate the critical droplet profile, the initial growth modes, and the exponent characterizing the divergence of the susceptibility near the spinodal. In the PDB model, we use a mean field analysis to calculate susceptibility exponent. We compare these theoretical results with Monte Carlo and Brownian dynamic simulations on the PS and PDB models, respectively. We find that by increasing the range of interaction, the system can be brought close to a pseudospinodal, and that in this region the nucleating droplet is diffuse in contrast to the compact droplets predicted by classical nucleation theory.