Collective Dynamics of Random Polyampholytes

TL;DR

This paper models the collective dynamics of semi-dilute random polyampholyte solutions, deriving their dynamic structure factor and potential matrix, and connecting their behavior to polyelectrolyte solutions in certain limits.

Contribution

It introduces a theoretical framework for the Langevin dynamics of random polyampholytes with charge fluctuations, using functional integral formalism and averaging over quenched disorder.

Findings

Dynamic structure factor computed for small charge fluctuations.

Effective collective potential matrix derived.

Scattering behavior approaches that of polyelectrolyte solutions at finite charge.

Abstract

We consider the Langevin dynamics of a semi-dilute system of chains which are random polyampholytes of average monomer charge $q$ and with a fluctuations in this charge of the size $Q^{-1}$ and with freely floating counter-ions in the surrounding. We cast the dynamics into the functional integral formalism and average over the quenched charge distribution in order to compute the dynamic structure factor and the effective collective potential matrix. The results are given for small charge fluctuations. In the limit of finite $q$ we then find that the scattering approaches the limit of polyelectrolyte solutions.