NANOTUBES MOTION ON LAYERED MATERIALS: A REGISTRY PERSPECTIVE

At dry material junctions of rigid materials the corrugation of the sliding energy landscape is dominated by variations of Pauli repulsions between electron clouds around atoms in adjacent layers as the slide upon each other. In such cases there exists a direct relation between superlubricity, a frictionless and wearless tribological state, and surface (in)commensurability. The Registry Index is a purely geometrical parameter that quantifies the degree of interlayer commensurability, thus providing a simple and intuitive method for the prediction of sliding energy landscapes at rigid material interfaces. In the present study, we extend the applicability of the Registry Index to non-parallel surfaces, using a model system of nanotubes on flat hexagonal materials. Our method successfully reproduces sliding energy landscapes of carbon nanotubes on Graphene calculated using a Lennard-Jones type and the Kolmogorov-Crespi interlayer potentials. Furthermore, it captures the sliding energy corrugation of a boron nitride nanotube on hexagonal boron nitride calculated using the h-BN ILP. Finally, we use the Registry Index to predict the sliding energy landscapes of the heterogeneous junctions of a carbon nanotubes on hexagonal boron nitride and of boron nitride nanotubes on graphene.