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A potential energy surface (PES)for bare, mono and di-hydrogenated nickel clusters is constructed using the extended-Hϋckel approximation. The parameters are optimized and good agreement with theoretical and experimental results is obtained without including a posteriori coordination dependent terms. The global minimum and the first few low-lying isomers of several nickel clusters are investigated using a variety of minimization techniques. The difference in energy between isomers is much smaller than the Ni-Ni dissociation energy. Both geometric and optical isomers are found for many cluster sizes. In some cases symmetric nuclear configurations give rise to orbital degeneracies in the adiabatic surface which lead to distortions. The hydrogen atom is most frequently found on the surface. All isomers of NinH2 contain a dissociated hydrogen molecule. The results are in good agreement with quantitative and qualitative experimental findings on this system.

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© 1998 American Institute of Physics.This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Curotto, E., A. Matro, David L. Freeman and J. D. Doll. ʺA Semi-Empirical Potential for Stimulations of Transition Metal Clusters: Minima and Isomer of N/sub n/(n=2-13) and Their Hydrides.ʺ Journal of Chemical Physics. 108(2):729-742. 8 January 1998 and may be found at