Structural Oscillation in Pd$_{13}$ During Oxidation/Reduction*

First principles electronic structure calculations within a gradient corrected density functional formalism have been carried out to investigate the electronic structure and magnetic properties of bare and oxidized Pd$_{13}$ clusters. It is shown that the ground state of neutral Pd$_{13}$ is a bilayer structure that can be regarded as a fragment of the bulk, while a compact icosahedron is higher in energy. The addition of an electron, however, reverses the ordering of structures and Pd$_{13}^{-}$ has an icosahedral ground state. Similar reordering of structure occurs as an O$_{2}$ molecule is added to the neutral cluster. The talk will focus on the oscillations between the two structures during catalysis process.