Structure of ${\mathrm{C}}_{20}$: Bicyclic ring versus cage

The relative stabilities of various geometries of 20-atom carbon cluters are investigated to determine the ground state, using a generalized tight-binding molecular dynamics technique. The 20-atom fullerene cage (relaxing to ${\mathrm{C}}_{\mathit{s}}$ symmetry due to Jahn-Teller distortion) is found to be the most stable structure even when compared to the recently proposed bicyclic ring structure.