We propose, on the basis of our first principles density functional based calculations, a new isomer of graphane, in which the C-H bonds of a hexagon alternate in 3-up, 3-down fashion on either side of the sheet. This 2D puckered structure called 'stirrup' has got a comparable stability with the previously discovered chair and boat conformers of graphane. The physico-chemical properties of this third 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 {\Gamma} point. Any other alternative hydrogenation of the graphene sheet disrupts its symmetric puckered geometry and turns out to be energetically less favorable.
@article{arxiv.1007.1864,
title = {The third conformer of graphane: A first principles DFT based study},
author = {A. Bhattacharya and S. Bhattacharya and C. Majumder and G. P. Das},
journal= {arXiv preprint arXiv:1007.1864},
year = {2011}
}