STRUCTURE OF CARBON CAPS AND FORMATION OF FULLERENES

Based on an assumption that carbon caps involving hexagons and pentago ns may be the intermediates in fullerene and buckytube formation proce sses, a theoretical study was performed on a model for the structures and closure of carbon caps. The results suggest that the carbon caps w ith six isolated pentagons seem to be more stable, and either couple t o produce fullerenes or grow to form cylindrical buckytubes by adding small carbon species to the dangling bonds. Using this model, various large isomeric fullerenes could be constructed by coupling two carbon caps with six isolated pentagons. The preferential formation of some s pecific isomers of fullerenes C-76 and C-84 was also predicted, in goo d agreement with previous experimental observations.