  The spectroscopic characteristics of systems with adsorbed d impurities on
noble metal surfaces should depend on the number and geometric arrangement of
the adsorbed atoms and also on their d band filling. Recent experiments using
scanning tunneling microscopy have probed the electronic structure of all 3d
transition metal impurities and also of Co dimers adsorbed on Au(111),
providing a rich variety of results. In this contribution we correlate those
experimental results with ab-initio calculations and try to establish necessary
conditions for observing a Kondo resonance when using the single impurity
Anderson model. We find that the relevant orbitals at the STM tip position,
when it is on top of an impurity, are the dThe spectroscopic characteristics of
systems with adsorbed d impurities on noble metal surfaces should depend on the
number and geometric arrangement of the adsorbed atoms and also on their d band
filling. Recent experiments using scanning tunneling microscopy have probed the
electronic structure of all 3d transition metal impurities and also of Co
dimers adsorbed on Au(111), providing a rich variety of results. In this
contribution we correlate those experimental results with ab-initio
calculations and try to establish necessary conditions for observing a Kondo
resonance when using the single impurity Anderson model. We find that the
relevant orbitals at the STM tip position, when it is on top of an impurity,
are the d orbitals with m=0 and that the energy of these levels with respect to
the Fermi energy determines the possibility of observing a spectroscopic
feature due to the impurity. orbitals with m=0 and that the energy of these
levels with respect to the Fermi energy determines the possibility of observing
a spectroscopic feature due to the impurity.
