Pentalene-based metallic and semiconducting nanostructures

Motivated by the recent progress in the atomic-level control of the morphology of carbon nanostructures we introduce the hexapentalene structures, which are two-dimensional systems assembled from pentalene-like building blocks. We use density functional theory to study their structure and their electronic properties. Hexapentalenes display an hexagonal symmetry and can be either metallic or semiconducting depending on the link between the molecular building blocks. These structures are found to be dynamically stable. We also study the electronic properties of nanoribbons formed by hexapentalene lattices and show that their electronic signatures closely follow those of their 2D counterparts, as their frontier states are mostly distributed not at their edges, but in the internal part of the nanoribbons. This finding is rationalized in terms of the wavelength of the low-energy states in the 2D systems, which are of the order of the narrowest ribbon widths.