Density-functional investigation of molecular graphene: CO on Cu(111)

TL;DR

This study uses density-functional theory to analyze how CO molecules arranged on Cu(111) create a molecular graphene with Dirac fermions, revealing electronic modifications and tunable properties consistent with experimental observations.

Contribution

It provides a detailed first-principles analysis of molecular graphene formed by CO on Cu(111), including electronic structure modifications and Dirac fermion behavior, with comparison to experiments.

Findings

CO molecules induce a hexagonal electron lattice on Cu(111)

Dirac fermion properties are tunable by CO density

Results align with experimental STM images

Abstract

Man-made artificial graphene has attracted significant attention in the past few years due to the possibilities to construct designer Dirac fermions with unexpected topological properties and applications in nanoelectronics. Here we use a first-principles approach within density-functional theory to study molecular graphene similar to the experiment by Gomes~{\em et al.}, Nature {\bf 483}, 306 (2012). The system comprises carbon monoxide molecules arranged on a copper (111) surface in such a way that a hexagonal lattice is obtained with the characteristic electronic properties of graphene. Our results show in detail how carbon monoxide molecules modify the copper surface (and regions beneath) and create a hexagonal lattice of accumulated electrons between the adsorbate molecules. We also demonstrate how the properties of the formed Dirac fermions change as the CO density is tuned, and provide a direct comparison with experimental scanning tunneling microscope images.