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O: Fachverband Oberflächenphysik

O 39: Heterogeneous Catalysis

O 39.7: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Suggestion to simulate energy dissipation via electron hole-pair – vibrational coupling using ab initio fitted TD-tight binding — Michael Grotemeyer and •Pehlke Eckhard — Institut für Theoretische Physik und Astrophysik, Universität Kiel, Germany

The ab initio molecular dynamics simulation of electronically non-adiabatic effects during the interaction (scattering or sticking) of atoms and molecules with solid surfaces using time-dependent density functional theory is computationally extremely expensive, even if simple Ehrenfest dynamics is assumed for the motion of the nuclei. This makes the required statistical averaging over initial conditions of the incoming particles impractical. For strong electron hole-pair – vibrational coupling between molecules and a metal surface, when most of the initial vibrational energy is dissipated during the incoming part of the trajectory (i.e. before reflection at the surface) an approximative approach appears to be feasible. The energy transfer into electron hole-pair excitations is estimated from the integration of a simple time-dependent 3D tight-binding hamiltonian with parameters adapted to ab initio data. In the TB model also distinctly thicker slabs than usually applied in density functional computations can be used, which alleviates the effects of finite bath size in case the simulation time corresponds to several vibrational periods of the molecular vibration. Aspects of this approach will be discussed.