Moiré pattern effect on sliding friction of two-dimensional materials

In two-dimensional materials, rotation induces Moiré patterns which have a crucial impact on friction. However, the relevance between Moiré patterns and friction is vague. By treating interlayer slide as the drift of Moiré patterns with near-invariable atomic configuration, we establish a clear relationship between Moiré patterns and potential energy corrugation. It is found that the negligible intrinsic corrugation for infinitely sized systems is resulted by the discrete distribution of local configurations inside the Moiré superlattices. As a result, the discrete corrugation is negatively correlated to the Moiré superlattice length. For finitely sized systems, the energy corrugation is mainly contributed by the irregular cutoff of Moiré periodicity. Under a few reasonable assumptions, the relationship between the cutoff corrugation and the ratio of slider size to Moiré superlattice length is derived. The same law applies to dynamic friction force. For friction force, both the irregular cutoff of Moiré periodicity and the edge effects are significant but the variation of the latter is subjected to the former.