Theoretical Studies of the Stability and Electronic Properties of Pd$_{n}$, and Pd$_{n}$O$_{2}$ (1$\le $n$\le $13) Clusters*

First principles electronic structure studies on the ground state geometry, electronic structure and magnetic moment of Pd$_{n}$(1$\le $n$\le $13) clusters have been carried out using a gradient corrected density functional approach. The clusters are found to be magnetic with a moment per atom that varies with cluster size. In particular, Pd$_{13}$ is shown to have a two layers structure that can be looked upon as a fragment of the bulk and has a spin magnetic moment of 6 Bohr magnetons. The calculated magnetic moments are compared with available data from Stern Gerlach experiments. We also study the effect of adding an O$_{2}$ molecule on the electronic and magnetic properties by carrying out corresponding studies on Pd$_{n}$O$_{2}$ (1$\le $n$\le $13) clusters. Our findings on the strength of binding of oxygen will be compared with recent experiments on the oxidation of palladium clusters by oxygen.