Local and nonlocal effects in the core ionization of metal-molecule adsorbates and cluster systems

An ab initio Green’s function comparative study of the $\mathrm{C}1\mathrm{}s$ ionization of PdCO and ${\mathrm{Pd}}_3\mathrm{CO}$ clusters has revealed distinct nonlocal effects in the spectrum of ${\mathrm{Pd}}_3\mathrm{CO}.$ A good agreement with the experimental $\mathrm{C}1\mathrm{}s$ spectrum of CO adsorbed on small Pd particles is achieved. A breakdown of individual charge transfer (CT) satellites associated with the basic PdCO unit of ${\mathrm{Pd}}_3\mathrm{CO}$ has been discovered. This breakdown is due to the coupling of the individual local CT states to a manifold of nonlocal double metal-adsorbate excitations and leads to a broadening of the giant satellites in adsorbate core-hole spectra.