Controlling the Kondo Effect in CoCu_n Clusters Atom by Atom
  Clusters containing a single magnetic impurity were investigated by scanning tunneling microscopy, spectroscopy, and ab initio electronic structure calculations. The Kondo temperature of a Co atom embedded in Cu clusters on Cu(111) exhibits a non-monotonic variation with the cluster size. Calculations model the experimental observations and demonstrate the importance of the local and anisotropic electronic structure for correlation effects in small clusters. 
N. Neel, J. Kroeger, R. Berndt, T. Wehling, A. Lichtenstein, M.I.   Katsnelson