Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Surface Dynamics
O 62.2: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-OG2
Energy dissipation at metal surfaces: The surprisingly high non-adiabaticity of Na diffusion on Cu(111) — •Simon P. Rittmeyer and Karsten Reuter — Technische Universität München
The role of electron-hole pair excitations during dynamical surface processes on metal substrates has been controversially discussed. With high-level non-adiabatic calculations still intractable for extended metal surfaces, the concept of electronic friction within the local density friction approximation (LDFA) offers approximate, but numerically highly efficient 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 to thermal surface diffusion, where non-adiabatic energy losses are expected to clearly compete with energy losses due to phononic coupling. In order to quantitatively disentangle these dissipation channels, we compare LDFA-based Langevin molecular dynamics simulations for Na on Cu(111) to experimental signatures obtained from state-of-the-art 3He spin echo measurements [2]. Despite the minimal electronic friction coefficient of Na and the relatively small mass mismatch to Cu promoting efficient phononic dissipation, we find that a surprisingly high amount of about 20% of the total energy loss is attributable to electronic friction.
S.P. Rittmeyer et al., Phys. Rev. Lett. 115, 046102 (2015).
S.P. Rittmeyer et al., Phys. Rev. Lett. 117, 196001 (2016).