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Sliding friction over individual aromatic bonds correlates with bond order
Shinjae Nam1,2, Lukas Hörmann3,4, Oliver Gretz1
1Faculty of Physics, University of Regensburg, Regensburg, Germany.
Nature Communications
|April 22, 2026
Summary
Researchers precisely measured atomic-level friction over chemical bonds. They discovered friction depends on bond order and electron density for aromatic bonds, and differs for hydrogen bonds, showing friction can be tuned.
Area of Science:
- Tribology
- Surface Science
- Quantum Chemistry
Background:
- Friction is a ubiquitous phenomenon crucial for many technological applications.
- Previous friction studies often lack atomic-level control and repeatability.
- Understanding friction at the atomic scale is key to its modification.
Purpose of the Study:
- To investigate friction at the single-atom level over individual chemical bonds.
- To determine the factors influencing energy dissipation during atomic-scale sliding.
- To compare friction mechanisms over aromatic and hydrogen bonds.
Main Methods:
- Lateral oscillation of a single-atom tip over individual chemical bonds.
- Measurement of energy dissipation during atomic-scale sliding.
- Density Functional Theory (DFT)-based simulations to analyze friction mechanisms.
Main Results:
- Energy loss over aromatic bonds was found to correlate with bond order and electron density.
- Friction over aromatic bonds is significantly influenced by increased electron density between atoms.
- Friction over hydrogen bonds showed similar magnitudes but different interaction mechanisms compared to aromatic bonds.
Conclusions:
- Atomic-scale friction is controllable by adjusting the bond order of sliding surfaces.
- Electron density plays a critical role in determining friction over aromatic bonds.
- Distinct mechanisms govern friction over different types of chemical bonds.
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