The binding of atomic hydrogen on graphene from density functional theory and diffusion Monte Carlo calculations

TL;DR

This study compares density functional theory and diffusion Monte Carlo methods to accurately determine the binding energy of atomic hydrogen on graphene, highlighting differences in results and charge distributions.

Contribution

It provides a detailed comparison of DFT and DMC calculations for hydrogen binding on graphene, improving understanding of their accuracy and differences.

Findings

PBE overestimates binding energy by about 20%.

HSE functional aligns DFT results closer to DMC.

Significant differences in charge distributions between methods.

Abstract

In this work density functional theory (DFT) and diffusion Monte Carlo (DMC) methods are used to calculate the binding energy of a H atom chemisorbed on the graphene surface. The Perdew-Burke-Ernzerhof (PBE) value of the binding energy is about 20% larger in magnitude than the diffusion Monte Carlo result. The inclusion of exact exchange through the use of the Heyd-Scuseria-Ernzerhof (HSE) functional brings the DFT value of the binding energy closer in line with the DMC result. It is also found that there are significant differences in the charge distributions determined using PBE and DMC approaches.