▎ 摘　　要

The relative stability of armchair, zigzag, and the reconstructed zigzag (reczag) graphene edges was studied density functional theory with the Perdew, Burke, and Ernzerhof (PBE) exchange correlation functional graphene nanoribbons in vacuo and on the Ru(0001) surface. Although the reczag edge was found to be stable in vacuo confirming previous predictions of Koskinen et al. [Phys. Rev. Lett. 101 (2008) 115502], the relative stability reverses upon adsorption on the Ru(0001) surface. The zigzag edge is more stathan the reczag edge on the surface by about 0.15 eV/angstrom and the armchair ribbon was found to be approximately isoenergetic with the zigzag ribbon. For all three types of edges, strong edge-Ru interactions are that cause the edges to buckle down. The lowered edge height may facilitate C attachments at graphene edges during graphene synthesis. (C) 2011 Elsevier B.V. All rights reserved.