Physical properties of a graphyne structure based on the Cmmm-graphene lattice.

Graphynes are 2D nanocarbon materials that combine sp and sp2 hybridized atoms in lattices usually derived from graphene. Here, we consider an alternative pathway where Cmmm-graphene is used as the backbone to build graphyne nanosystems. We used density functional theory to investigate the physical properties of the resulting graphyne systems, focusing on their electronic properties. We show that the graphynic systems exhibit frontier states that form Dirac cones at the Fermi level, in contrast to the parent sp2 system, which is semiconducting. We further study nanotubes and nanoribbon realizations of the proposed graphyne. We demonstrate that additional boundary conditions modulate the electronic behavior of these graphynic quasi-1D systems, including the interaction between the nanotube set of cutting lines and the Dirac cones of the 2D systems in the Brillouin zone, as well as the chirality-dependent edge states.