Stretching helical nano-springs at finite temperature

TL;DR

This paper investigates the elastic behavior of helical nano-springs under tension using simulations and analytics, revealing temperature-dependent phenomena like stretching instability, melting, and the influence of boundary conditions.

Contribution

It provides a comprehensive analysis of the finite-temperature elastic response of helical filaments, highlighting the effects of temperature, persistence length, and boundary conditions.

Findings

Low-temperature helix shows stretching instability with force spikes.

High-temperature helix melts, producing a force plateau.

Torque boundary conditions significantly influence elastic properties.

Abstract

Using dynamic simulations and analytic methods, we study the elastic response of a helical filament subject to uniaxial tension over a wide range of bend and twist persistence length. A low-pitch helix at low temperatures exhibits a stretching instability and the force-extension curve consists of a sequence of spikes. At elevated temperature (i.e. small persistence lengths) the helix melts and a pronounced force plateau is obtained in the fixed-extension ensemble. The torque boundary condition significantly affects the resulting elastic properties.