Topological phonon modes in filamentous structures

TL;DR

This paper introduces a new class of topological phonon modes in quasi-one-dimensional filamentous structures with inversion symmetry, exemplified by actin Microfilaments, suggesting their potential ubiquity in biological systems.

Contribution

It presents the first detailed analysis of topological phonon modes in filamentous structures with inversion symmetry, expanding the understanding of their occurrence beyond 2D systems.

Findings

Topological phonon modes are stable and localized at edges of filamentous structures.

The studied structure is the simplest supporting topological phonon modes.

Biological structures like Microfilaments may utilize topological phonon modes.

Abstract

Topological phonon modes are robust vibrations localized at the edges of special structures. Their existence is determined by the bulk properties of the structures and, as such, the topological phonon modes are stable to changes occurring at the edges. The first class of topological phonons was recently found in 2-dimensional structures similar to that of Microtubules. The present work introduces another class of topological phonons, this time occurring in quasi one-dimensional filamentous structures with inversion symmetry. The phenomenon is exemplified using a structure inspired from that of actin Microfilaments, present in most live cells. The system discussed here is probably the simplest structure that supports topological phonon modes, a fact that allows detailed analysis in both time and frequency domains. We advance the hypothesis that the topological phonon modes are ubiquitous in the biological world and that living organisms make use of them during various processes.