Effects of lattice structure on the electronic properties of helically symmetric nanotubes

In the last decades, nanotubes with varied compositions, underlying lattice structures, and symmetries have been proposed. In this work, we theoretically investigate nanotubes with similar compositions and symmetries but with different underlying lattice structures. Our aim is to understand how the underlying lattice structure of the nanotubes may affect their electronic properties. In order to do so, helically symmetric BCN nanotubes with graphene and graphenylene lattice structures were studied. In the considered structures, helical stripes of C atoms were incorporated into BN nanotubes with different helical angles. The geometric optimizations of the helical structures were carried out by using the Parametric Method 3 (PM3), whereas the electronic properties were calculated within the Green function formalism by using the Rubio–Sancho technique. Our results indicate that the stability of the two types of nanotube follows a similar pattern, with the energy per atom increasing as the fraction of C–N and C–B bonds increases. On the other hand, the type of lattice plays a critical role in the electronic properties. Although all considered helically symmetric nanotubes are semiconductors, different underlying lattice structures lead to distinct features. Graphene lattice nanotubes present a tunable band gap, whereas graphenylene lattice nanotubes present a nearly constant band gap for all helical angles. By focusing on the role of the underlying lattice structure, our work highlights how strain or stress, associated with each underlying lattice structure, may be tools to customize the properties of the nanotubes.