Strain-induced Dirac cone-like electronic structures and   semiconductor-semimetal transition in graphdiyne
  By means of the first-principles calculations combined with the tight-binding approximation, the strain-induced semiconductor-semimetal transition in graphdiyne is discovered. It is shown that the band gap of graphdiyne increases from 0.47 eV to 1.39 eV with increasing the biaxial tensile strain, while the band gap decreases from 0.47 eV to nearly zero with increasing the uniaxial tensile strain, and Dirac cone-like electronic structures are observed. The uniaxial strain-induced changes of the electronic structures of graphdiyne come from the breaking of geometrical symmetry that lifts the degeneracy of energy bands. The properties of graphdiyne under strains are disclosed different remarkably from that of graphene. 
Hui-Juan Cui, Xian-Lei Sheng, Qing-Bo Yan, Qing-Rong Zheng, and Gang   Su
cond-mat.mtrl-sci