Comment on Band structure engineering of graphene by strain: First-principles calculations

In their first-principles calculations of the electronic band structure of graphene under uniaxial strain, Gui, Li, and Zhong, [Phys. Rev. B 78, 075435 (2008)] have found opening of band gaps at the Fermi level. This finding is in conflict with the tight-binding description of graphene which is closed gap for small strains. In this Comment, we present first-principles calculations which refute the claim that strain opens band gaps in graphene.