Molecular dynamics simulation of the self-retracting motion of a graphene flake

TL;DR

This study uses molecular dynamics simulations to analyze the self-retracting behavior of graphene flakes, revealing how initial orientation affects motion barriers and highlighting potential for fast electromechanical memory devices.

Contribution

It demonstrates the influence of initial commensurate states and rotation on graphene flake retraction, and compares dynamic friction effects with carbon nanotubes.

Findings

Incommensurate initial states lead to barrierless retraction.

Rotation to incommensurate states is induced by torque.

High dynamic friction suppresses oscillations, unlike in nanotubes.

Abstract

The self-retracting motion of a graphene flake on a stack of graphene flakes is studied using molecular dynamics simulations. It is shown that in the case when the extended flake is initially rotated to an incommensurate state, there is no barrier to the self-retracting motion of the flake and the flake retracts as fast as possible. If the extended flake is initially commensurate with the other flakes, the self-retracting motion is hindered by potential energy barriers. However, in this case, the rotation of the flake to incommensurate states is often observed. Such a rotation is found to be induced by the torque acting on the flake on hills of the potential relief of the interaction energy between the flakes. Contrary to carbon nanotubes, telescopic oscillations of the graphene flake are suppressed because of the high dynamic friction related to the excitation of flexural vibrations of the flake. This makes graphene promising for the use in fast-responding electromechanical memory cells.