A density functional study of CoCn (n=1-8) clusters:: Structures and stabilities

A theoretical study of the different linear, fan and cyclic CoCn (n = 1-8) clusters has been carried out. Predictions for their electronic energies, rotational constants, dipole moments, and harmonic vibrational frequencies have been made using the B3LYP method with the 6-311 + G(d) basis set. Doublet and quartet lowest-lying states have been found for neutral COCn clusters. The stability of linear, fan, and cyclic structures as a function of the size of the cluster has been discussed in terms of the incremental binding energies. Only fan structures show a clear even-odd alternation in stability. The incremental binding energies exhibit small changes along the series in the case of linear isomers, whereas for cyclic ones decrease along the series. It is also found that for the small COCn clusters in general, the linear-type structures are more stable than the fan and cyclic ones. (c) 2008 Wiley Periodicals, Inc.