Computational studies of silver clusters adsorbed on AgBr cubic surfaces

Silver dusters adsorbed to different sites on cubic AgBr surfaces have been treated by classical and quantum mechanical methods. The properties comput ed include structure, bond energies, and ionization energies. The optimized geometry of the adsorbed silver cluster tends to be planar up to and inclu ding four atoms in size. Distinct odd-even oscillations in the ionization p otential and electron affinity, similar to those known in the gas phase, ar e found for the adsorbed silver clusters. The site of adsorption exerts a s trong effect on the calculated energy levels consistent with Coulombic reas oning based upon formal partial site charges. Structural relaxation of the clusters plays an important role in their electron accepting properties. Th e Ag, and Ag,clusters have a large ionization potential, which correlates w ith high stability. The Ag, cluster is less stable, due to midgap levels ca pable of accepting electrons or holes. Overall, the calculations are consis tent with the nucleation and growth model of latent image formation.