Institute of Solid State Physics
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SS22 WS22 SS23 WS23 SS24 WS24 Guidelines for Master Students
Atomic-scale insights into frictional energy dissipation mechanisms during single-molecule manipulation 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, and machine learning and use the probe particle model to simulate energy dissipation. Using this approach, we investigate dynamic friction at the natural limit of a singular atom moving a single chemical bond. This enables us to explore how the local bonding environment of the underlying sample surface affects the energy dissipation that a probe particle experiences. Focussing on the example of a CO-functionalised lateral force microscope that measures frictional energy dissipation above various organic adlayers on Cu(111), we find strong correlations between the local bonding environment and the energy dissipation. Our findings capture the qualitative trends found in experiment. We explore the influence of thermal activation on the CO-tip overcoming barriers in the potential energy surface and examine the role of electron-nuclei coupling in the energy dissipation of a CO molecule adsorbed on a metal apex. Finally, we present a mechanistic interpretation of our results that provides insights into the underlying physics of atomic/lateral force microscopy measurements. |
