Hydrogen adatoms on graphene: the role of hybridization and lattice distortion

TL;DR

This paper investigates how hydrogen adatoms affect graphene's electronic properties, revealing that hybridization dominates over lattice distortion and enabling a simplified impurity model for low concentrations.

Contribution

It introduces a compact tight-binding model for hydrogen-adsorbed graphene that accounts for hybridization and limited impurity interactions, scalable with impurity number.

Findings

Lattice deformation has minimal impact on p_z orbital coupling.

Hybridization occurs mainly between hydrogen s orbitals and graphene p_z orbitals.

Impurity interactions are limited to nearby atoms, enabling a scalable model.

Abstract

Hydrogen adatoms on graphene are investigated using DFT and analytical approaches. We demonstrate that the level of lattice deformation due to the hydrogen adsorption does not substantially change the coupling between the graphene $p_{z}$ orbitals. The hybridization primarily takes place between the adsorbate's s orbital and the graphene $p_{z}$ orbitals. We also show that the impurity interaction with the graphene atoms is limited to only a few nearest neighbors, allowing us to construct a compact TB model for the impurity-graphene system with an arbitrary impurity distribution. The complexity of our model scales with the number of impurities, not their separation, making it especially useful in the study of low impurity concentrations.