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 states 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 (scattering and emission processes). Interesting many-body effects are expected due to the large Coulomb repulsion in the atom site. In this work the time-dependent Keldysh Green functions defined in a mixed space of fermions and bosons with the constraint of a total number Q = 1, are calculated by using the equation of motion method. The dynamical equations obtained in this form allow to calculate the charge state of the moving atom, and in the stationary limit they reproduce a spectral density of states with properties in an excellent agreement with exact results. (C) 2001 Elsevier Science B.V. All rights reserved.