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The development and reconstruction of surface structures formed by underpotential deposition (UPD) of Cu atoms on Pt(100) and Pt(ll1) clusters are approached through extended Hiickel molecular orbital (EHMO) calculations applied to a statistical Cu atom deposition.These results allow us to obtain a qualitative description of the different stable configurations of Cu atoms on the Pt cluster surfaces in terms of the corresponding binding energies.

The aim of this paper is to report a study of the reactivity of Pt(lOO) cluster and the same system modified by a nickel tetramer towards the atomic hydrogen adsorption. This study was carried out in the framework of density functional theory which provides global and local indexes that can be used to characterize the reactivity. The analyzed reactivity descriptors were: chemical potential, chemical hardness, electrophilicity index and Fukui function. The results showed that the global reactivity descriptor predicts that the platinum cluster modified by nickel is more reactive than the pure platinum cluster and that the local Fukui function provides information about the most susceptible site to electrophilic attack in platinum cluster.