Metastable spin - polarized carbon clusters C 8 and their ensembles

Results of tight-binding calculations on metastable spin-polarized carbon clusters C 8 (prismanes) are presented. It is shown that those clusters can form ensembles due to intercluster bonding. The binding energy of a given metastable configuration decreases monotonously with the total spin S, while the activation energy for the decay of a metastable state has distinct maxima as a function of S. For specific values of S, the dynamical stability of spin-polarized ensembles of prismanes appears to be higher than that of an isolated prismane, pointing to a possibility of existence of " cluster matter " composed of spin-polarized clusters C 8. Carbon is a chemical element with a great number of unique properties. In particular , carbon is known by its polymorphism. Due to its ability to exist in different valence states, carbon can form a rich variety of compounds, including diamond, graphite, carbyne, etc. In the field of nanostructures, cage-like fullerenes (C 60 etc. [1]) attract much attention due to their both practical and fundamental importance. Recently, the cage-like cluster C 20 was synthesized [2]. This cluster is the smallest possible fullerenes cage consisting of 12 pentagons. First-principle calculations [3] point to a possibility of synthesis of condensed C 20 phases with three-dimensional 1 covalent networks. In recent numerical simulations of small carbon clusters, a possible existence of another cage-like cluster C 8 (prismane) was suggested theoretically [4]. Prismane was predicted to have the shape of a six-atom triangular prism with two excess atoms above and below its bases, see Fig.