STRUCTURE AND ENERGETICS OF SINGLE AND MULTILAYER FULLERENE CAGES

Minimum energy structures for large carbon cages are investigated usin g realistic atomic potentials. Above a critical size of approximately 6000 there is a stability crossover from single to multilayer cages. T he lowest energy atomic configuration of a cage of any size consists o nly of hexagons and pentagons and is polyhedral in shape. Lowest energ y defects involve either rearrangements between pentagons and hexagons or 5-7-5 triplets. Simulated transmission electron microscopy images show that a polyhedral onion appears spheroidal when viewed along its highest symmetry axis, and polyhedral when viewed from a more general direction.