Atomistic simulations of formation and stability of carbon nanorings

Atomistic simulations of the formation and stability of nanorings through the energy relaxation of geometrically folded single-walled carbon closed rings are performed using the second-generation reactive bond-order potential. It is found that the critical diameter for forming a stable nanoring can be made significantly smaller than that observed in experiments. The critical diameter for an armchair nanoring is smaller than that for a zigzag nanoring with the same nanotube diameter. The effect of torsion on a nanoring reduces its critical diameter. A large flattening of the nanotube cross section is found to be effective for the reduction in stress and stiffness of the nanoring. In addition, the instability of a nanoring always starts with the formation of short wavelength ripples on the compressed side of the nanotube. Subsequently, some ripples will develop into buckles, resulting in buckling failures.