Chiral γ-graphyne nanotubes with almost equivalent bandgaps.

Analogous to conventional carbon nanotubes, single-walled, chiral, γ-graphyne nanotubes (C-γGyNTs) are modeled based on the synthesized 2D γ-graphyne motif, and their electronic properties are investigated via density-functional tight-binding calculations for the first time. The resulting γGyNTs are predicted to be excellent semiconductors with moderate bandgaps ranging from 1.291 eV to 1.928 eV. In addition, the bandgaps of zigzag γGyNTs and armchair γGyNTs show damped oscillatory behaviour, while those of C-γGyNTs do not show any chirality- or diameter-dependent oscillatory behaviour. Interestingly, it is revealed that the (2a, m)-γGyNTs, where a is a positive integer, have nearly identical bandgap values, which provides a fresh method of bandgap manipulation for semiconductor devices that has not yet been reported.