Van der Waals interactions of parallel and concentric nanotubes

TL;DR

This paper develops an extended density functional theory approach to accurately describe van der Waals interactions in carbon nanotube systems, addressing limitations of standard DFT for sparse materials.

Contribution

It introduces a new electron-density based extension of DFT to model van der Waals forces between parallel and concentric nanotubes.

Findings

Consistent description of fully screened van der Waals interactions

Effective modeling of nanotube bundling and multiwalled structures

Addresses DFT limitations in sparse carbon nanostructures

Abstract

For sparse materials like graphitic systems and carbon nanotubes the standard density functional theory (DFT) faces significant problems because it cannot accurately describe the van der Waals interactions that are essential to the carbon-nanostructure materials behavior. While standard implementations of DFT can describe the strong chemical binding within an isolated, single-walled carbon nanotube, a new and extended DFT implementation is needed to describe the binding between nanotubes. We here provide the first steps to such an extension for parallel and concentric nanotubes through an electron-density based description of the materials coupling to the electrodynamical field. We thus find a consistent description of the (fully screened) van der Waals interactions that bind the nanotubes across the low-electron-density voids between the nanotubes, in bundles and as multiwalled tubes.