First-Principles Analysis of Corrugations, Elastic Constants, and Electronic Properties in Strained Graphyne Nanoribbons

Density functional calculations have been performed to analyze atomic corrugations, Young's modulus, Poison's ratio, and the electronic structure of monolayer graphyne ribbons under uniaxial strains within generalized gradient approximations. Within particular asymmetrical critical compressive (epsilon(c)(cr)) and tensile (epsilon(t)(cr)) strains, graphyne ribbons will undergo a reversible deformation, which is interpreted within a framework of linear elastic stress-strain response. From the energy-displacement relations, the two-dimensional Young's modulus is obtained, and it increases along with the width increasing. When the compressive strain is beyong epsilon(c)(cr), unidirectional corrugations perpendicular to the strain direction are formed in wider ribbons. When the tensile strains exceed epsilon(t)(cr), all ribbons undergo longitudinal corrugations before fracture. The corrugation wavelength is practically not dependent on the applied strain but on the ribbon width. All these ribbons are semiconductor with controllable band gaps of 0.14-1.22 ev, depending on the width and the applied strain. Furthermore, the band gaps of graphyne ribbons are sensitive to the tensile strain and can be continuously modulated regardless of the critical strain because the bands near the Fermi level are split off 2p(z) states and mainly composed of pi orbitals of benzenes in the graphyne sheet.