Electronic properties of small free Co clusters

We present a systematic study of the average magnetic moments and the non-m etal-metal transition of free Co-N clusters having different geometries: he xahedral, octahedral and decahedral. The electronic structure is calculated with a parameterized Hubbard Hamiltonian with spd electrons within the unr estricted Hartree-Fock approximation, and spill-over effects are considered . We compare our calculations with other theoretical calculations in the li terature. We also comment on the experimental results.