Abstract
We performed ab initio calculations to study the effect of out-of-plane deformation on the electronic structures of graphene nanoribbons. We find that the band gap of severely curved GNR is significantly modified and a semiconductor-metal transition can be observed under the radial deformation. The band gap changes mainly arise from the hybridization of sigma and pi orbitals and the modification of orbital interactions. It is possible that good geometry control can result in semiconductor-metal transition in deformed graphene nanoribbons.