Structural and electronic properties of double-walled α-graphyne nanotubes

The structural and electronic properties of double-walled alpha-graphyne nanotubes (alpha-DWGNTs) are investigated using a combination of computation and theoretical methods, including density functional theory. DWGNTs differ from conventional double-walled carbon nanotubes by the presence of carbon atoms featuring both sp and sp2 hybridizations, endowing DWGNTs with a set of desirable properties that could lead to a number of applications. Classical molecular dynamics (MD) and Born-Oppenheimer molecular dynamics (BOMD) simulations were performed to reveal the structural stability of these nanotubes at room temperature. Their dynamical stability was confirmed using tight-binding based phonons calculations. The high flexibility of the graphyne sheet and van der Waals interactions between the shells lead to strong deformations of the outer tube. Consequently, the electronic structure of the component single-walled tubes undergoes significant changes once cast into the double-walled geometries due to the coupling of electronic states from the inner wall with the outer tube. Such strong inter-wall hybridization can not only modulate the electronic band gap of semiconducting tubes, in comparison to their isolated single-walled counterparts, but can also affect the electronic properties of the double-walled systems. These behaviors open up possibilities of using such nanostructures in the design of electronic device applications.