We propose, on the basis of our first-principles density functional based calculations, an interesting isomer of graphane in which the C-H bonds of a hexagon alternate in three-up–three-down fashion on either side of the sheet. This two-dimensional puckered structure, called “stirrup,” has an intermediate stability between the previously reported chair and boat conformers of graphane. The physicochemical properties of this conformer are found to be similar to the other two conformers of graphane with an insulating direct band gap of 3.1 eV at the Γ point. Any other alternative hydrogenation of the graphene sheet disrupts its symmetrically puckered geometry and turns out to be energetically less favorable than these three conformers.

• Received 9 July 2010

DOI:https://doi.org/10.1103/PhysRevB.83.033404