Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 7: Surface reactions I

O 7.3: Vortrag

Montag, 27. März 2006, 11:45–12:00, WIL C207

Non-adiabatic spin-transfer and electronic friction during chemisorption simulated with TDDFT — •Eckhard Pehlke and Michael Lindenblatt — Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität Kiel, 24098 Kiel

When atoms interact with a surface, part of their chemisorption energy is transferred into electron-hole pair excitations. This can result in the emission of exoelectrons, or chemicurrents over Schottky barriers as observed by Nienhaus et al. [1]. We simulate such non-adiabatic processes using time-dependent spin-density functional theory together with Ehrenfest dynamics for the motion of the nuclei. Results for the chemisorption of H-atoms on the Al(111) surface will be presented. Upon approach of the surface, the local spin polarization of the hydrogen atom is transferred to the substrate electrons. For an incoming H-atom with thermal energies, the energy dissipated into electron-hole pairs amounts to order of 0.1 eV for the initial part of the trajectory up to the first reflection of the H atom at the surface potential. The variation of the local spin polarization at the H-atom is compared to the Newns-Anderson model by Mizielinski et al. [2].

[1] H. Nienhaus, Surf. Sci. Rep. 45, 1 (2002).

[2] M.S. Mizielinski, D.M. Bird, M. Persson, S. Holloway, J. Chem. Phys. 122, 084710 (2005).