Ab initio study of edge effect on relative motion of walls in carbon nanotubes

TL;DR

This study uses density functional theory to analyze how edge effects influence the relative motion of walls in carbon nanotubes, revealing sensitivity to edge structure and potential for nanomechanical applications.

Contribution

It provides the first detailed ab initio analysis of edge effects on interwall interactions and motion in double-walled nanotubes, including force and temperature estimates.

Findings

Edge structure significantly affects energy corrugation and motion barriers.

Threshold forces and transition temperatures for wall motion are estimated.

Edges contribute notably to rotational barriers in nonchiral walls.

Abstract

Interwall interaction energies of double-walled nanotubes (DWNTs) with long inner and short outer walls are calculated as functions of coordinates describing relative rotation and displacement of the walls using van der Waals corrected density functional theory. The magnitude of corrugation and the shape of the potential energy relief are found to be very sensitive to changes of the shorter wall length at subnanometer scale and atomic structure of the edges if at least one of the walls is chiral. Threshold forces required to start relative motion of the short walls and temperatures at which the transition between diffusive and free motion of the short walls takes place are estimated. The edges are also shown to provide a considerable contribution to the barrier to relative rotation of commensurate nonchiral walls. For such walls, temperatures of orientational melting, i.e. the crossover from rotational diffusion to free relative rotation, are estimated. The possibility to produce nanotube-based bolt/nut pairs and nanobearings is discussed.