Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: Surface Chemical Dynamics
O 14.11: Vortrag
Montag, 7. März 2016, 17:45–18:00, S053
Adatom Diffusion on Metal Surfaces: Disentangling Phononic and Electronic Energy Dissipation — •Simon P. Rittmeyer, Patrick Gütlein, and Karsten Reuter — TU München
The role of electron-hole pair excitations during dynamical surface processes on metal substrates has been controversially discussed. While adiabatic first-principles calculations often provide a satisfactory description, an abundance of such excitations is generally suggested by the continuum of electronic states around the Fermi level. With high-level non-adiabatic calculations still untractable for extended metal surfaces, the concept of electronic friction within the local density friction approximation (LDFA) offers numerically efficient, but approximate insight.
We have recently shown this approach to yield reasonable results for the vibrational damping of high-frequency adsorbate vibrations on various metal surfaces [1]. With this confidence we now apply it for surface diffusion, where non-adiabatic energy losses compete with energy losses due to phononic coupling. We compare our LDFA-based molecular dynamics simulations for various alkali-metal adsorbates on Cu(111) to experimental signatures obtained from 3He spin echo measurements [2]. This comparison allows to decompose empirically obtained friction coefficients into electronic and phononic contributions for the first time.
S.P. Rittmeyer et al., Phys. Rev. Lett. 115, 046102 (2015).
D.J. Ward, PhD thesis, University of Cambridge (2013).