  Ballistic conductance through a single atom adsorbed on a metallic surface
and probed by a scanning tunneling microscope (STM) tip can be decomposed into
eigenchannel contributions, which can be potentially obtained from shot noise
measurements. Our density functional theory calculations provide evidence that
transmission probabilities of these eigenchannels encode information on the
modifications of the adatom's local density of states caused by its interaction
with the STM tip. In the case of open shell atoms, this can be revealed in
nonmonotonic behavior of the eigenchannel's transmissions as a function of the
tip-adatom separation.
