Silicon-based counterpart of alpha-graphyne

We present the first principles density functional calculations of electronic structure and energetics of silicon-based counterpart of α-graphyne, labeled as α-silicyne. Both LDA and GGA functionals are applied for exchange-correlation potentials. We show that graphyne-like silicon in 2D buckled structure (equilibrium buckling δz≅0.73 and Δz≅1.45Å) has 2.33eV and 1.96eV lower energies than planar geometry for GGA and LDA functionals, respectively. The single and triple bond lengths of silicon are consistent with previously reported values. As a different case from graphyne, which is semimetallic, the electronic band structures of buckled α-silicyne do not show Dirac fermion indicating a metallic nature. The metallic character of the system is largely determined by p-electronic states of the triple bonded silicon atoms.