What happens when Graphene is folded multiple times?

Experimental techniques for folding graphene at specific locations and orientations have already been reported. Elucidating the nanoscale structures and electronic properties obtained by folding graphene in this manner presents an intriguing research topic. This study reports computational simulation results concerning the atomic structure of graphene folded multiple times on a flat substrate. The Tersoff potential was used for intra-layer covalent bonding, and the Lennard-Jones potential for inter-layer van der Waals interactions. We discovered that in multi-folded graphene, interactions between the folded layers form characteristic atomic structures not observed in single-folded graphene. Furthermore, we observed that these atomic structures undergo qualitative changes depending on the size of the folding.Various shapes and sizes of void structures appear in the gaps between the folded layers. We discuss the potential for diverse electronic states reflecting these void structures. We also discuss the appearance of moiré patterns depending on the bending angle and the electronic properties reflecting this moiré.