Tunable Electronic Properties in Molecular Graphene*

We uncover the electronic structure of molecular graphene [1] produced by adsorbed CO molecules on a copper (111) surface by means of first-principles (density-functional theory) calculations [2]. Our results show that the band structure is fundamentally different from that of conventional graphene, and the unique features of the electronic states arise from co-existing honeycomb and Kagome symmetries. Furthermore, the Dirac cone does not appear at the K-point but at the Γ-point in the reciprocal space, and it is accompanied by a third, almost flat band. Calculations of the surface structure with Kekulé distortion show a gap opening at the Dirac point in agreement with experiments. Finally, we use our computational approach to assess the feasibility of the system as an electronic Lieb lattice according to recent experiments [3].
References:
[1] K. K. Gomes et al., Nature 483, 306 (2012).
[2] S. Paavilainen et al., Nano Letters 16, 3519 (2016).
[3] M. R. Slot et al., Nature Physics 13, 672 (2017).