Band Structure and Quantum Conductance of Nanostructures from Maximally-Localized Wannier Functions: The Case of Functionalized Carbon Nanotubes

TL;DR

This paper presents a method combining large-scale electronic-structure calculations with Wannier functions to efficiently analyze band structures and conductance in complex nanostructures, applied specifically to functionalized carbon nanotubes.

Contribution

It introduces a first-principles approach for calculating band structure and conductance in large systems, applied to covalently functionalized nanotubes, revealing effects of functionalization patterns.

Findings

Band structure less dependent on ligand chemistry than on functionalization pattern.

Aryl functionalizations are more stable with hydrogen pairing.

Functionalizations act as scattering centers reducing conductance.

Abstract

We have combined large-scale, $\Gamma$-point electronic-structure calculations with the maximally-localized Wannier functions approach to calculate efficiently the band structure and the quantum conductance of complex systems containing thousands of atoms while maintaining full first-principles accuracy. We have applied this approach to study covalent functionalizations in metallic single-walled carbon nanotubes. We find that the band structure around the Fermi energy is much less dependent on the chemical nature of the ligands than on the $sp^3$ functionalization pattern disrupting the conjugation network. Common aryl functionalizations are more stable when paired with saturating hydrogens; even when paired, they still act as strong scattering centers that degrade the ballistic conductance of the nanotubes already at low degrees of coverage.