Thermally Activated Snap-through Transitions Controlled by Tunable Metastability

TL;DR

This paper demonstrates how thermally activated snap-through transitions in graphene nanoribbons can be predicted and controlled using advanced sampling and transition state theories, enabling design of nanoscale thermal devices.

Contribution

It introduces a theoretical framework combining enhanced sampling and transition state theory to analyze thermally activated transitions in nanomechanical systems.

Findings

Transition rate constants depend predictably on temperature.

Free energy landscapes can be mapped using well-tempered metadynamics.

Generalized transition state theory accurately models transition kinetics.

Abstract

The effects of thermal fluctuations on the morphology of two-dimensional materials are hard to harness. We propose that a geometrically constrained graphene nanoribbon (GNR) can exhibit thermally activated snap-through transitions with a predictable and controllable transition rate constant. The energetics and kinetics of such transitions can be fully captured by combining enhanced sampling methods and generalized transition state theory. Using well-tempered metadynamics, we determine the free energy landscape and a pair of asymmetric transition pathways of the GNR system. Notably, generalized transition state theory accurately captures how the transition rate constant responds to temperature and the tunable free energy landscape of our system. This work offers a theoretical framework for elastic metastability, introduces rare event methods into thermalized nanomechanical systems, and provides potential applications in designing nanoscale thermal switches and thermal actuators.