A first-principles study on the electromechanical effect of graphene nanoribbon

The electromechanical effect of graphene nanoribbons (GNRs) is investigated via a first-principles method. The deformations of GNRs with zigzag shaped edges (ZGNR) and armchair shaped edges (AGNR) are considered. The nonlinear stress-strain relations are found for both of the AGNRs and the ZGNRs. The AGNRs seem to be stiffer than the ZGNRs as concluded from inspecting the Young's modulus and the ideal strength of GNRs. It is found that a mechanical deformation will affect the electronic structures of GNRs. The band gap of AGNRs exhibits sawtooth oscillations under strains and the oscillating strength is up to 1 eV. On the contrary, the band gap of ZGNRs is insensitive to strain. However, the band gap of ZGNRs will be reduced dramatically to zero as the compressive strain is greater than 0.17. The large variation of the band gap of AGNRs under strain indicates that deformation can provide an opportunity for tuning the band gap of an AGNR.