We have used a first-principles molecular-dynamics technique to find the relaxed atomic geometries and the corresponding electronic structures of three of the simplest novel forms of three-coordinated solid carbon. We compare the energies of these structures to those of graphite and of the icosahedral fullerene C60. All of these forms of carbon contain only one kind of carbon atom. One of these, which we name polybenzene, is found to have a substantially lower energy per atom (0.23 eV) than C60, yet contains only 24 atoms per unit cell.

http://dx.doi.org/10.1103/PhysRevLett.68.2325