Understanding the atomic-scale friction in graphene: The distinction in behaviors of interlayer interactions during sliding

The atomic-scale friction in the graphene system is investigated from the interlayer interaction perspective using the density functional theory calculation including the dispersion correction. The structural effect brings a huge difference in friction between the commensurate and incommensurate states, and the interlayer interactions behavior quite differently as well. The van der Waals and π electron interactions, which comprise the interlayer interactions in the graphene system, act synergistically for the commensurate state. The energy barrier and hence friction are dominated by the van der Waals interaction for the relatively lower load, while the π electron interaction plays a more important role for the higher load. For the incommensurate state, the van der Waals interaction does not vary much during sliding, and the energy barrier and friction are mainly induced by the interaction between π electrons from different layers. The study increases our understanding on the interlayer interaction and friction mechanism in graphene and other carbon-based materials.