Sequence randomness and polymer collapse transitions

TL;DR

This paper demonstrates that chain disorder with frustration can alter the universality class of the theta transition in heteropolymers, challenging previous expectations based on Harris' criterion.

Contribution

It provides evidence that beyond a certain frustration threshold, disorder influences the scaling behavior at the polymer collapse transition.

Findings

Disorder with frustration modifies universality class at theta transition.

Scaling exponents deviate from homopolymer values when frustration exceeds threshold.

Exact enumeration and Monte Carlo methods confirm the transition shift.

Abstract

Contrary to expectations based on Harris' criterion, chain disorder with frustration can modify the universality class of scaling at the theta transition of heteropolymers. This is shown for a model with random two-body potentials in 2D on the basis of exact enumeration and accurate Monte Carlo results. When frustration grows beyond a certain finite threshold, the temperature below which disorder becomes relevant coincides with the theta one and scaling exponents definitely start deviating from those valid for homopolymers.