Structure and electronic properties of graphyne layers modeled on layers of graphene L3-12

摘要

In the present paper, a theoretical study of the structure and electronic properties of new polymorphic conformations ofgraphyne layers modeled on layers of graphene L3–12 was performed. Graphyne layers have been constructed by replacingcarbon-carbon bonds between three-coordinated (sp2-hybridized) atoms in the graphene layer of L3–12 with diatomic carbynechains. Geometric optimization and examination of electronic properties of novel graphyne architectures were performedwithin the framework of density functional theory using the gradient approximation. Calculations have shown the possibilityof stable existence of three main polymorphic conformations of graphyne layers. Te graphyne layers were designed byincorporating a carbyne chain into the initial L3–12-graphene layer by following rules: for the γ-L3–12-graphyne layer, one bondof each three-coordinated atom was substituted by a carbyne chain, for the β-L3–12-graphyne layer, two bonds of those atomswere replaced, and for α-L3–12-graphyne layers three bonds were replaced. Te sublimation energy of the graphyne layers is inthe range from 6.52 to 6.61 eV/atom that is less than the sublimation energy of the original L3–12 graphene layer (6.66 eV/atom)as well as the sublimation energy of hexagonal graphene (7.76 eV/atom). However, the value of the sublimation energy of thegraphyne layers is in the range of experimentally synthesized carbon materials that are stable under normal conditions. All thegraphyne layers studied in this work are semiconductors with the energy gaps widths from 0.18 to 0.91 eV.