A new proposal to solve the time-dependent infinite-U Anderson model applied to ion-surface scattering processes

The interaction between delocalized conduction band states and localized st ates on an atom site is well described by an Anderson Hamiltonian. The time dependence of this Hamiltonian comes from the trajectory dependence of the parameters in processes where there are atoms moving near a surface (scatt ering and emission processes). Interesting many-body effects are expected d ue to the large Coulomb repulsion in the atom site. In this work the time-d ependent Keldysh Green functions defined in a mixed space of fermions and b osons with the constraint of a total number Q = 1, are calculated by using the equation of motion method. The dynamical equations obtained in this for m allow to calculate the charge state of the moving atom, and in the statio nary limit they reproduce a spectral density of states with properties in a n excellent agreement with exact results. (C) 2001 Elsevier Science B.V. Al l rights reserved.