Electronic structure of small clusters of nickel and iron

We have performed self-consistent, spin-polarized calculations for free Fe₁₃, Ni₁₃, and Ni₁₉ clusters with face-centered-cubic geometry and for a Fe₁₄C cluster with body-centered-cubic geometry. The calculations are made by expansion in a basis set of Gaussian orbitals. Results are discussed in relation to similar calculations for bulk metals. Comparison of the present results with our previous calculations for Fe₁₅ shows that the d-level distribution in the nickel cluster is narrower in comparison with the bulk than was found for iron, but that the spin distribution is closer to the bulk. The central atom in the Fe₁₃ cluster is strongly spin polarized oppositely to the surrounding atoms. Effects due to replacement of the central iron atom in Fe₁₅ by carbon are studied. The ionization potential of Fe₁₃ was found to be 5.41 eV.