Prismane C8:: a new form of carbon?

Our numerical calculations on small carbon clusters point to the existence of a metastable three-dimensional eight-atom cluster Cg which has a shape of a six-atom triangular prism with two excess atoms above and below its bases. We gave this cluster the name "prismane." The binding energy of prismane is 5.1 eV/atom, i.e., 0.45 eV/atom lower than the binding energy of the stable one-dimensional eight-atom cluster and 2.3 eV/atom lower than the binding energy of bulk graphite or diamond. Molecular dynamics simulations give evidence for a rather high stability of prismane, the activation energy for prismane decay being about 0.8 eV. The prismane lifetime increases rapidly as the temperature decreases, indicating the possibility of experimental observation of this cluster. (C) 1998 American Institute of Physics. [S0021-3640(98)00821-4].