Density Functional Investigation of Graphene Nanoribbons

Density functional theory calculations have been performed on graphene nano ribbons (GNRs) of dimension from 7.27 Å to 16.11 Å along x-axis, 4.93 Å to 9.91 Å along y axis for armchair nanoribbons and 5.99 Å to 18.73 Å along x-axis 8.28 Å to 11.65 Å along y-axis for zigzag nanoribbons. Density functional theory calculations have been performed on graphene nano ribbons (GNRs) to investigate the electronic properties as a function of chirality, size and hydrogenation on the edges. The calculations were performed on GNRs with armchair and zigzag configurations with 28, 34, 36, 40, 50, 56, 62, 66 carbon atoms. The structural stability of AGNR and ZGNR increases with the size of nanoribbon where as hydrogenation of GNR tends to lowers their structural stability. All GNRs considered have shown semiconducting behavior with HOMO-LUMO gap decreasing with the increase in the GNR size. The hydrogenation of GNR decreases its HOMO-LUMO gap significantly. The results are in agreement with the available experimental and theoretical results.