AVS 52nd International Symposium
    Surface Science Thursday Sessions
       Session SS2-ThA

Paper SS2-ThA8
First Principles Resonance Energies and Widths of Ions near Surfaces: N-Body Dynamical Predictions of Charge-Transfer Probabilities for Scattered Ions

Thursday, November 3, 2005, 4:20 pm, Room 203

Session: Gas-Surface Reaction Dynamics
Presenter: K. Niedfeldt, Princeton University
Authors: K. Niedfeldt, Princeton University
E.A. Carter, Princeton University
P. Nordlander, Rice Univeristy
Correspondent: Click to Email
By combining periodic density-functional theory calculations of adsorbate resonance widths and shifts with a many-body dynamical charge-transfer theory, we quantitatively assess charge-transfer rates for ions scattering off surfaces. This method goes beyond previous approaches, which have been limited to modeling metal surfaces with either jellium potentials or finite clusters. We consider Li+ scattering off Si(001), Mg(0001), Cu(001), and Al(001). When compared to experimental neutralization fractions for Li ion scattering off of Al(001), our method yields trends in neutralization as a function of scattering angle in better agreement than those derived from jellium models. Our results comparing Mg and Cu show that scattering off of Mg and Cu yield distinctly different charge-transfer probabilities. By contrast, jellium predicts identical scattering properties due to identical theoretical free-electron gas values. As expected, for Li ions scattering off Si(001), the Li 2s orbital interacts most strongly with the Si dimer dangling bonds. The charge-transfer rates for Li ions scattering off Si(001) exhibits extreme variations with lateral position, in contrast again to the jellium picture. Taken together, these results clearly indicate that more realistic ion-surface interaction models (such as provided here) are necessary to obtain even qualitatively correct trends in charge-transfer for many ion-surface interactions.