C20: fullerene, bowl or ring? New results from coupled-cluster calculations

Contrary to recent experimental evidence suggesting that the monocyclic ring is the most stable 20-atom carbon species, highly accurate calculations convincingly predict that the smallest fullerene, dodecahedral C20, has the lowest energy. A related corannulene-like bowl is nearly degenerate in energy to the fullerene. Thermodynamic considerations suggest that at formation temperatures of around 700 K the bowl should be the dominant species.