Inertia and Activity: Spiral transitions in semi-flexible, self-avoiding polymers

TL;DR

This study investigates how activity and inertia influence the shape and dynamics of semi-flexible, self-avoiding polymers, revealing a re-entrant transition between motile chains and spirals, with inertia playing a key destabilizing role at higher activity levels.

Contribution

It introduces a phase diagram showing the impact of activity and inertia on polymer configurations, highlighting inertia's role in spiral destabilization at high activity.

Findings

Spiral formation occurs at low activity, independent of inertia.

Inertia destabilizes spirals at high activity levels.

Non-monotonic divergence from equilibrium with activity.

Abstract

We consider a two-dimensional, tangentially active, semi-flexible, self-avoiding polymer to find a dynamical re-entrant transition between motile open chains and spinning achiral spirals with increasing activity. Utilizing probability distributions of the turning number, we ascertain the comparative stability of the spiral structure and present a detailed phase diagram within the activity inertia plane. The onset of spiral formation at low activity levels is governed by a torque balance and is independent of inertia. At higher activities, however, inertial effects lead to spiral destabilization, an effect absent in the overdamped limit. We further delineate alterations in size and shape by analyzing the end-to-end distance distribution and the radius of gyration tensor. The Kullback-Leibler divergence from equilibrium distributions exhibits a non-monotonic relationship with activity, reaching a peak at the most compact spirals characterized by the most persistent spinning. As inertia increases, this divergence from equilibrium diminishes.