Adsorbed 3d transition-metal atoms and dimers on Au(111): Signatures derived from one-electron calculations

Abstract

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 (STM) have probed the electronic structure of all 3d transition-metal impurities and also of Co dimers adsorbed on Au(111). 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 level determines the possibility of observing a spectroscopic feature due to the impurity.