Effective mass and band gap of strained graphene

•The electronic structure of strained graphene.•Band gap engineering of strained graphene.•Advantages of tight binding schemes in graphene electronic structure.•Isotropic versus uniaxial strained graphene.

The effective mass of strained graphene is investigated by tight-binding and density-functional theory calculations. For graphene strained in the zigzag direction, we find a strong anisotropy in the effective mass near the gap opening, with an abrupt increase of the effective mass at the critical strain in one direction and a smooth variation perpendicular to it. There is no band-gap opening for isotropic strain, but at an expansive strain of about 28%, the lower edge of the s-band reaches the Fermi level and makes the graphene metallic.