Point defect formation energies in graphene from diffusion quantum Monte Carlo and density functional theory

Thomas, David and Asiri, Yassmin and Drummond, Neil (2022) Point defect formation energies in graphene from diffusion quantum Monte Carlo and density functional theory. Physical Review B: Condensed Matter and Materials Physics, 105. ISSN 1098-0121

[img]
Text (graphene_paper)
graphene_paper.pdf - Accepted Version
Available under License Creative Commons Attribution-NonCommercial.

Download (5MB)

Abstract

Density functional theory (DFT) is widely used to study defects in monolayer graphene with a view to applications ranging from water filtration to electronics to investigations of radiation damage in graphite moderators. To assess the accuracy of DFT in such applications, we report diffusion quantum Monte Carlo (DMC) calculations of the formation energies of some common and important point defects in monolayer graphene: monovacancies, Stone-Wales defects, and silicon substitutions. We find that standard DFT methods underestimate monovacancy formation energies by around 1 eV. The disagreement between DFT and DMC is somewhat smaller for Stone-Wales defects and silicon substitutions. We examine vibrational contributions to the free energies of formation for these defects, finding that vibrational effects are non-negligible. Finally, we compare the DMC atomization energies of monolayer graphene, monolayer silicene, and bulk silicon, finding that bulk silicon is significantly more stable than monolayer silicene by 0.7522(5) eV per atom.

Item Type:
Journal Article
Journal or Publication Title:
Physical Review B: Condensed Matter and Materials Physics
Additional Information:
© 2022 American Physical Society
ID Code:
171111
Deposited By:
Deposited On:
01 Jun 2022 09:25
Refereed?:
Yes
Published?:
Published
Last Modified:
28 Jan 2023 01:20