Structural and electronic properties of collapsed armchair single-walled [formula omitted]-graphyne nanotubes

Abstract

The properties of radially collapsed armchair single-walled α-graphyne nanotubes (α-SWGNTs) are investigated using density functional theory with van der Waals (vdW) corrections. Here, our main goal is to study the structural properties of stable collapsed SWGNT forms and how the corresponding electronic structure are modified in comparison to the circular counterparts. The presence of carbon atoms with sp and sp2 hybridization makes the SWGNTs to present an intriguing geometry for their cross section in the collapsed form and, as a result, the electronic structure of these system is sensitivity to the stacking mode between layers. We find a threshold diameter (26 Å) for which the collapsed structure is more stable than the circular phase, indicating that the natural form of large SWGNTs is radially collapsed. Furthermore, we identified that the collapsed structure is semiconductor when the diameter of the circular phase is greater than 19 Å, with band gap values adjusted by the type of stacking between layers. We believe these results can open up possibilities of using such structures in the setups of nanoelectronic device, and provide a basis for future experimental and theoretical research about collapsed graphyne nanotubes.