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We constructed α-graphyne nanotubes (αGyNTs) and performed density functional theory calculations to investigate the electronic properties of zigzag and armchair αGyNTs. We found that all zigzag graphyne nanotubes (Z-αGyNTs) were semiconductors. In particular, the band gap of Z-αGyNTs showed an oscillatory dependence on tube size which could be further classified into three families with N z = 3 m − 1, 3 m and 3 m + 1 where m is a positive integer. This resulted in band gap magnitudes in the following rank order: 3 m − 1 > 3 m + 1 > 3 m. Armchair αGyNTs were also calculated to be semiconductor with very small band gaps when tube size is small, though they become metallic as the tube size increases. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were carried out to investigate how single-atom vacancies affect the electronic and magnetic properties of three types of graphyne model systems. Our simulations demonstrate that a single-atom vacancy can lead to an in-plane structural rearrangement, which plays an important role in tuning the electronic structures. A dispersionless spin-polarized band was observed around the fermi level, inducing strong magnetism in the three graphyne models. The single-atom vacancy can induce a 1.1–1.3 μ B magnetic moment into αGy and βGy, while this value increases significantly to about 1.8μ B for γGy. This single-atom vacancy technique is a promising method of manipulating the electronic and magnetic properties of graphyne. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were carried out to study how the position of single-atom doping affects the electronic properties of three graphyne models. We found that the position of the dopant (B, N, or O) plays an important role in tuning the electronic structure of graphynes. For α-graphyne, the electronic structure is significantly different for different positions of B and O doping. For β-graphyne, the electronic structure depends remarkably on the doping position for O doping, but not much for B and N doping, whereas for γ-graphyne, it depends on the position for B and O doping, but not for N doping. [ABSTRACT FROM AUTHOR]