First-principles study of bandgap effects in graphene due to hydrogen adsorption

TL;DR

This study uses first-principles calculations to analyze how hydrogen adsorption affects the electronic bandgap in graphene, revealing periodicity-dependent effects and providing insights for improved modeling.

Contribution

It demonstrates the dependence of hydrogen-induced bandgap effects on periodicity and offers explanations based on ab initio Hamiltonian analysis, enhancing tight-binding models.

Findings

Bandgap opens at the Dirac point due to hydrogen adsorption.

Periodicities with a scale factor of three suppress the bandgap.

The study provides a Hamiltonian-based explanation for band structure changes.

Abstract

Hydrogen adsorption on graphene in commensurate periodic arrangements leads to bandgap opening at the Dirac point and the emergence of dispersionless midgap bands. We study these bandgap effects and their dependence on periodicity for a single hydrogen adsorbate on periodic graphene supercells using spin-polarized density-functional theory calculations. Our results show that for certain periodicities, marked by a scale factor of three, the bandgap is suppressed to a great extent, and has a special level structure around the neutrality point. We present explanations for the origin of the changes to the band structure in terms of the \textit{ab initio} Hamiltonian matrix. This method may be used to obtain a more accurate tight-binding description of single hydrogen adsorption on graphene.