Coalescence of fullerene cages: Topology, energetics, and molecular dynamics simulation

Sequential atomic rearrangements leading to the coalescence of fullerene cages or tubes are derived by topological analysis. Qualitative reasoning assists the search for the minimum-energy path, which consists of a jump-to-contact formation of covalent bonds between the separate cages and the following ``plastic flow'' by exclusively Stone-Wales bond rotations. A connecting neck forms and grows gradually until the separate clusters are completely fused into a coherent unit. The most favorable path is determined by comparison of the calculated energies and is further supported by molecular dynamics simulations. Results are presented for C₆₀+C₆₀, C₆₀+tube, cap-to-cap, cap-to-wall, and wall-to-wall coalescence of nanotubes of different types.