  Control of the edge topology of graphene nanostructures is critical to
graphene-based electronics. A means of producing atomically smooth zigzag edges
using electronic current has recently been demonstrated in experiments [Jia et
al., Science 323, 1701 (2009)]. We develop a microscopic theory for
current-induced edge reconstruction using density functional theory. Our
calculations provide evidence for localized vibrations at edge-interfaces
involving unpassivated armchair edges. We demonstrate that these vibrations
couple to the current, estimate their excitation by Joule heating, and argue
that they are the likely cause of the reconstructions observed in the
experiments.
