Structures of Binary C60-C84 fullerene clusters.
A systematic study of the potential energy global minimum (GM) structures of model binary fullerene clusters of compositions (C(60))(n)(C(84))(N-n), N </= 24 has been carried out using the basin-hopping method. The stiff Girifalco pair potential is used. We report a novel GM geometry for (C(84))(13) with D(5) geometry. To the best of our knowledge, this is the first reported homogeneous 13-particle cluster whose potential is pairwise additive that has this structure. For homogeneous fullerene clusters larger than N = 13, the dominant packing motif is decahedral. By contrast, for the binary clusters studied, polyicosahedral structures are observed for a broad range of cluster sizes and compositions. It is pointed out how the favorable size ratio reduces strain to produce these packing motifs. For N = 23 and N = 24, we observe a reduced strain "stacked" polyicosahedral motif between the compact polyicosahedral and decahedral stability regions. Mackay-icosahedron based GMs were found for clusters (C(60))(1) (C(84))(N-1), N > 18.
Department of Chemistry, University of New Hampshire, Durham, New Hampshire 03824, USA.
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