Structures, binding energies, and charge distributions for two to six atom Ti, Cr, Fe, and Ni clusters and their relationship to nucleation and cluster catalysis

Abstract

In a low spin molecular orbital approximation, binding energies and optimized structures for various two to six atom clusters of Ti, Cr, Fe, and Ni are calculated. Ti, with few d electrons, shows a preference for tightly packed clusters with positively charged corner atoms while Ni favors open and ringlike clusters with negatively charged corner atoms; Cr and Fe, with nearer to half‐filled d shells, prefer tightly packed configurations, but charge distributions are less predictable. The parameterization and spin models used in the theoretical procedure are considered. The binding energies, structures, and charge distributions are discussed in relation to transition metal cluster catalysis and experimental Fe nucleation studies. The photoemission spectra for O and CO on a nine atom Fe (100) model cluster are calculated and are found to be similar, within calculational and experimental resolution, to those for the Fe(100) surface.