Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 31: Focus Session Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation II

O 31.6: Vortrag

Dienstag, 18. März 2025, 12:00–12:15, H24

Electronic and phononic frictional dissipation in single-molecule dynamics at CO-decorated tips — •Lukas Hörmann and Reinhard J. Maurer — University of Warwick, Coventry, UK

Friction causes significant energy loss in any moving mechanical device. As the miniaturisation of devices reaches the quantum limit, so do dynamical dissipation processes. Fundamentally quantum mechanical mechanisms govern friction at the nanoscale. We account for all relevant quantum mechanical effects, such as charge transfer, or van der Waals interactions, by employing density functional theory, machine learning, and non-adiabatic molecular dynamics. Using this approach, we investigate friction energy dissipation at the natural limit of singular atoms. This allows us to explore how the local electronic and geometric structure affects the dissipation of mechanical energy, where electron-phonon and phonon-phonon coupling give rise to electronic and phononic excitations. Focusing on the example of CO on various Cu surface geometries, we find that electron-phonon coupling strongly depends on the local electronic density of states, while the geometric structure significantly influences phonon-phonon coupling. Our findings quantitatively agree with experiment. Finally, we present a mechanistic interpretation of our findings that provides insights into the underlying physics of single-molecule dynamics on surfaces.

Keywords: atom-scale friction; electron-phonon coupling; phonon-phonon coupling; density functional theory