Theoretical identification of C20 carbon clusters:: Prevalence of the monocyclic isomer and existence of the smallest fullerene and bowl isomer -: art. no. 125415

Free energies, electron affinities, and vibrational progressions have been investigated for several competitive C-20 isomers by using ab initio calculations. The dominant C-20 species generated by vaporizing graphite is first clarified. It turns out to be the monocyclic ring, followed by the tadpoles (a short chain attached to a monocyclic ring), linear chain and bicyclic rings. On this basis, the two recently synthesized C-20 isomers [Prinzbach, Nature (London) 407, 60 (2000)] may be exclusively attributed to the fullerene and bowl structures respectively in these competitive C-20 isomers. Therefore, the existences of the smallest fullerene and C-20 bowl isomer appear to be fully confirmed.