Density functional study of the ionization potentials and electron affinities of small Nin clusters with n=2-6 and 8

The ionization potentials and electron affinities Of Ni-n clusters, with n = 2-6 and 8, are studied in this work using the generalized gradient approximation to the density functional theory. Important changes observed after geometry and spin multiplicity optimization suggest that the ionization processes under study cannot be simply described as the result of the removal or addition of an electron from or to the corresponding neutral system. Our results indicate that both ionization processes mainly involve electrons having s or sp dominant characters. Experimental ionization potentials are very well reproduced by the present theoretical results. The experimental electron affinities, on the other hand, are systematically underestimated by the present calculations although the overall trend is well reproduced. (C) 2004 Elsevier B.V. All rights reserved.