Attraction-Induced superlubricity and its detection

A nanoscale friction test using an atomic force microscope (AFM) is modelled as a diatomic tip in sliding contact with a 2D monolayer supported by a metal substrate. This test is simulated by ab initio DFT calculations. The simulation results show that, when a silver tip slides on a honeycomb borophene (HB) monolayer supported by a titanium substrate, the friction force varies nonlinearly with the prescribed height of the tip or, equivalently, the corresponding normal force exerted by the tip on the HB monolayer. In particular, the friction force turns out to be almost null when the height of the tip sufficiently approaches a critical height of the prescribed height, which corresponds to a critical normal attraction force. This nanoscale friction-free sliding phenomenon is thus qualified as attraction-induced superlubricity (AISL). Further, the origin of AISL is discussed and analyzed in terms of electron redistributions. Finally, the feasibility of AISL detection is argued by analyzing the potential energy surface (PES), the adsorption strength of the tip on HB surface and the binding strength of HB to its substrate.

Automated summary

In this study, a nanoscale friction test using an atomic force microscope (AFM) is simulated by ab initio DFT calculations. The results show that when a silver tip slides on a honeycomb borophene monolayer supported by a titanium substrate, the friction force varies nonlinearly with the tip height and becomes almost zero near a critical height. This phenomenon is called attraction-induced superlubricity (AISL), and its origin is discussed in terms of electron redistributions.