Energetics and electronic structures of polymerized cyclobutadiene

Abstract

We investigated electronic and geometric properties of polymerized cyclobutadiene (C4) as a metallic form of a two-dimensional carbon allotrope using first-principles calculations. Our calculations show that the polymerized structure is stable with a total energy that is slightly higher than that of C60 fullerene and close to that of small fullerene polymers. This two-dimensional covalent network with tetragonal symmetry is a metal with linear dispersion bands at the Fermi level due to the inflection point in the cosine bands. We also studied the stable stacking arrangement and electronic structures of layered system comprising the C4 polymer. The calculations show that the AA stacking is a favorable stacking arrangement among four representative stacking structures. Although small but substantial interlayer interaction, electronic structures of the layered system of C4 polymer are almost the same as that of the monolayer of C4 polymer.