Electronic properties of four typical zigzag-edged graphyne nanoribbons

The subband structures and edge magnetism of alpha-, beta-, gamma-and (6, 6, 12)-graphyne nanoribbons with zigzag edges are studied by means of ab initio calculations. Dispersionless subbands and antiparallel edge magnetic ordering occur in these nanostructures, just like in zigzag-edged graphene nanoribbons. More importantly, a very simple tight-binding model is established which can accurately describe the subband structures of these ribbons. From such a model we find that beta-graphyne nanoribbon has many more transport modes than other graphyne and graphene nanoribbons, hence it can carry a much larger current. Such a tight-binding model provides a simple but effective way to study further the transport and optical properties of these graphyne nanoribbons.