Fullerene genesis by ion beams .2. Disclinations and the corranulene road

A new defect-based model for the growth of the fullerene molecule, C-60, assembling from a hot, homogenous and dense ensemble of carbon atoms, or ''primeval soup'', is presented. Routes comprising swift open channels to fullerene pass through a succession of carbon clusters which are characterised by ''magic'' numbers related to high reactivity and maximization of the number of dangling bonds per cluster. There is a critical high temperature nucleation leap into three dimensions at the corranulene kernel C-20. This is determined by the appearance of a pentagon-based defect, the wedge disclination, which is then in turn responsible for the growth of C-60, multiple (or ''hedge-hog'') disclinations, higher order fullerenes, nested (and seeded) onion-like clusters and, ultimately, tiny crystalline stable polyhedra. Disclinations play a role in the development of three-dimensional aromatic molecules similar to that of screw dislocations in crystal growth.