The DFT and molecular dynamics multiscale study of the corrugation of graphene on Ru(0001): the unexpected stability of the moire-buckled structure

Abstract

Results from first principles density functional theory (DFT) calculations and classical molecular dynamics (CMD) simulations are presented on moire-corrugation of graphene (gr). We find that the moire-corrugated graphene could be surprisingly stable against the perfectly flat gr-sheet as pointed out by CMD simulations and DFT calculations. We also show that using the cost-effective CMD approach one can simulate graphene on e.g. Ru(0001) with a correct binding registry and reasonable corrugation and adhesion energy. A new force field has been parameterized for the interface using an angular-dependent Abell-Tersoff potential. The newly parameterized Abell-Tersoff interface potential provides correct moire superstructures in accordance with scanning tunnelling microscopy images and with DFT results. Based on ab initio DFT calculations, we also find that the CMD moire superstructure can be used as a preoptimized structure for DFT calculations and for further geometry optimization. The nearly flat gr (the corrugation $\xi \approx 0.2$ $\hbox{\AA}$) on Ru(0001) is slightly energetically unfavorable vs. the moire-corrugated gr-system ($\xi \approx 2.0$ $\hbox{\AA}$) as revealed by van der Waals DFT structural relaxation.