Glassy phases in Random Heteropolymers with correlated sequences

TL;DR

This paper introduces a new analytical approach using the cavity method to study dense phases of correlated heteropolymers, revealing three distinct phases including a novel soft glass phase, with implications for understanding polymer behavior.

Contribution

The paper develops a cavity method-based mean field approach that accurately captures nearest neighbor correlations in heteropolymers with correlated sequences, identifying a new soft glass phase.

Findings

Identification of three dense phases: liquid, soft glass, and frozen glass.

Prediction of the soft glass phase in polyampholytes with alternating sequences.

The approach handles local correlations exactly and can be extended to other systems.

Abstract

We develop a new analytic approach for the study of lattice heteropolymers, and apply it to copolymers with correlated Markovian sequences. According to our analysis, heteropolymers present three different dense phases depending upon the temperature, the nature of the monomer interactions, and the sequence correlations: (i) a liquid phase, (ii) a ``soft glass'' phase, and (iii) a ``frozen glass'' phase. The presence of the new intermediate ``soft glass'' phase is predicted for instance in the case of polyampholytes with sequences that favor the alternation of monomers. Our approach is based on the cavity method, a refined Bethe Peierls approximation adapted to frustrated systems. It amounts to a mean field treatment in which the nearest neighbor correlations, which are crucial in the dense phases of heteropolymers, are handled exactly. This approach is powerful and versatile, it can be improved systematically and generalized to other polymeric systems.