Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)

O 41.46: Poster

Dienstag, 23. März 2010, 18:30–21:00, Poster B1

Ab initio molecular dynamics simulation of electronic energy dissipation: HCl/Al(111) — •Michael Grotemeyer and Eckhard Pehlke — Institut für Theoretische Physik und Astrophysik, Universität Kiel, Germany

The scattering of vibrationally excited HCl molecules from Au(111) has been studied experimentally and interpreted in view of electronically nonadiabatic processes [1]. We present ab initio molecular dynamics simulations of the scattering of highly vibrationally excited HCl molecules at Al(111). The time-dependent Kohn-Sham equations are integrated numerically for the electrons, and the positions of the ions follow Ehrenfest dynamics. The electronic excitation along the trajectory is obtained from comparison of the time-dependent electronic structure with the electronic ground state at the respective frozen-in ionic positions. Reducing numerical expenses, the simulations are carried through for mass-scaled systems. Under the assumption of linear friction, the dissipation is extrapolated to the physical masses of the ions [2]. For not vibrating HCl molecules we obtain only a faint energy transfer into electron-hole pairs. Electronic energy dissipation is significant for a strongly vibrating HCl molecule in front of Al(111). Different geometries with either the H-or Cl-atom pointing towards the surface are compared. We note that electronic friction has turned out not to be enhanced for a situation where the H-atom points towards the surface and oscillates in the charge density tail of the metal.

[1] I. Rahinov et al., J. Chem. Phys. 129. 214708 (2008).

[2] M. Lindenblatt and E. Pehlke, Surf. Sci. 23, 5068 (2006).