FOLDING MECHANICS OF BI-LAYER GRAPHENE SHEET

Abstract

Folding in graphene sheet has been extensively observed experimentally. While it is generally recognized that such a conformational state can influence the electronic, magnetic and mechanical properties of graphene nanostructures, the mechanism driving the nonlinear mechanical deformation remains an interesting subject of study. Here we present an investigation on the folding in bi-layer graphene sheet due to in-plane compression. To describe the lattice registry effect of interlay cohesion in layered graphitic structures, a registry-dependent potential model was implemented. We have determined the critical length to stabilize the graphene folding to be 5.4~10.7 nm through both theoretical and simulation analysis. The mechanism for such a stabilized fold is attributed to the variations in the inter-layer interaction energy that produces a friction-like effect. The climbing image nudged elastic band (CINEB) calculations predicted an identical activation energy barrier associated with the transition between flat and folded configurations, 0.47 eV/Å, for graphene sheets with length of 7~10 nm. When the mechanical stimulation is high enough to overcome the energy barrier, the supported graphene sheet can be folded to form a nanotube.