Tracking the mechanism behind graphene ripple inversion with LAMMPs

Freestanding graphene spontaneously forms ripples. If a sheet is under sufficient compressive strain, the ripples form a bi-stable system (concave or convex). The rate at which a ripple inverts is lower than the small thermal oscillation frequency. This rate decreases with increased compressive strain, and increases with increased temperature. We ran ten simulations, using LAMMPs molecular dynamics simulation software, for a single ripple of graphene, with different compressive strains at 3000 K. The z-component (out of plane) average and center values were tracked to identify when inversion occurs. Atoms that make up a cross-section of the ripple were also tracked. Changes in the cross-section profile that occur during inversion show that the mechanism behind inversion is the formation of smaller sub-ripples.