Mechanical and Electronic Properties of Graphyne and Its Family under Elastic Strain: Theoretical Predictions

Using the first-principles calculations, we investigate the mechanical and electronic properties of graphyne and its family under strain. It is found that the in-plane stiffness decreases with increasing the number of acetylenic linkages, which can be characterized by a simple scaling law. The band gap of the graphyne family is found to be modified by applying strain through various approaches. While homogeneous tensile strain leads to an increase in the band gap, the homogeneous compressive strain as well as uniaxial tensile and compressive strains within the imposed range induce a reduction in it. Both graphyne and graphyne-3 under different tensile strains possess direct gaps at either M or S point of Brillouin zone, whereas the band gaps of graphdiyne and graphyne-4 are always direct and located at the Γ point, irrespective of strain types. Our study suggests a potential direction for fabrication of novel strain-tunable nanoelectronic and optoelectronic devices.