Uniaxial strain in graphene and armchair graphene nanoribbons: An ab initio study

摘要

We report first-principles studies on the electronic and vibrational properties of uniaxially strained graphene and graphene nanoribbons. The band structure of extended graphene shows an interesting behavior under uniaxial strain in directions other than the zigzag or armchair direction. While strained graphene remains semi-metallic, one-dimensional graphene nanoribbons allow band-gap tuning via strain. The shift of the strain-induced band-gap in armachair nanoribbons depends on their family. At small strain the band-gap of all AGNRs depends linearly on the amount of strain. Concerning the vibrational spectra, we compare strain-induced shift rates of the G modes in two-dimensional graphene and AGNRs. The shift rates of the G- and G+ modes in AGNRs strongly reflect the common classification into three families. For large ribbon widths all shift rates converge to their counterparts in graphene.