Structures and stabilities of charged cobalt-doped carbon clusters

The structure and properties of the different linear, fan and cyclic isomers of CoCn+ and CoCn− (n = 1–8) clusters have been calculated using the B3LYP method with the 6–311+G(d) basis set. The stability of clusters as a function of the size has been discussed in terms of the incremental binding energies. Linear, fan and cyclic structures of CoCn+ clusters show a clear even–odd alternation in stability, n-odd members being more stable than the corresponding n-even ones. An opposite parity effect is found for linear and fan CoCn− clusters, whereas the relative stability of cyclic isomers decrease with n. Linear structures are the most stable CoCn+ and CoCn− clusters, with the only exception of CoC2+/− and CoC7− where the fan and cyclic arrangements are slightly lower in energy. The computed ionization potentials for the three structures show a clear even–odd alternation, with higher values for n-even clusters than for n-odd ones. Electron affinities for CoCn clusters increase along the series.