Local electronic structure around a single Kondo impurity

The local electronic structure due to the adsorption of Co on Cu(111) is studied using an embedded cluster model, in which the crystal background is taken into account via an effective density functional theory (DFT)-based potential. This approach goes beyond the usual single-impurity Anderson model, where the ground state consists of a singly occupied impurity whose moment is compensated by the background conduction electrons. Ab initio correlated wave function calculations for the embedded cluster provide an alternative picture for this ground state and indicate that the quenching of the Co magnetic moment is due to the formation of metal-metal bonds with the Cu substrate. Low-lying excitations are also studied within the embedding model, and our results are discussed in the context of scanning tunneling microscopy experiments (Manoharan, H.C.; Lutz, C.P.; Eigler, D.M. Nature 2000, 403, 512), which find a sharp tunneling resonance localized in the vicinity of the Co adatom.