Electronic and transport properties of graphene nanoribbons

We perform ab initio calculations for graphene nanoribbons (GNRs) using density-functional theory (DFT) and generalized gradient approximation (GGA) functionals. We present results for the dependence of the band structures and energy gaps on the ribbon widths for armchair and zigzag GNRs. The influence of spin polarization and spin ordering on the band structure is studied for zigzag GNRs. The electronic band structures are then converted into transmission functions using a number-of-states approach derived from the Landauer-Büttiker formalism. For several groups of armchair and zigzag GNRs, the similarities and differences of the quantum transport are discussed.