AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM8
Newns-Anderson Model for Chemicurrents

Monday, November 15, 2004, 10:40 am, Room 210B

Session: Electronic Structure and Excitations
Presenter: S. Holloway, University of Liverpool, UK
Authors: S. Holloway, University of Liverpool, UK
D. Bird, University of Bath, UK
M. Mizielinski, University of Bath, UK
M. Persson, Chalmers University of Technology, Sweden
Correspondent: Click to Email
The excitation of electron-hole pairs when a reactive species adsorbs on a surface should invariably be expected but it has proved difficult to quantify the strength of the process. We have performed first principles calculations for the interaction of a hydrogen atom with a Cu surface to investigate the chemicurrent induced. This calculation involves calculating the electronic response to the adsorbate motion and then using a forced oscillator description for the energy dissipation. Results will be presented for hydrogen and deuterium and comparison made with recent experiments. The numerical results are consistent with values derived from experiment for the H-Cu system. Application of the standard spin-polarised DFT approach results in a phase transition that occurs as the resonance intercepts the Fermi level. This, in turn, gives rise to an infinitely strong dissipative force above the metal which results in unphysical dynamics even before the atom encounters the adsorption well. The origin of the problem has been traced back to the nearly adiabatic assumption that is made in the standard application of time dependent DFT to electronic friction. In this present work, we deploy the Newns-Anderson description and show that this rather unexpected behaviour can be quite straightforwardly understood. Furthermore, we present for the first time, results for the chemicurrent using a new theoretical approach based on the time-dependent Newns-Anderson model.