Interlayer registry to determine the sliding potential of layered metal dichalcogenides: The case of 2H -MoS ₂

We provide a simple and intuitive explanation for the interlayer sliding energy landscape of metal dichalcogenides. On the basis of the recently introduced registry index (RI) concept, we define a purely geometrical parameter that quantifies the degree of interlayer commensurability in the layered phase of molybdenum disulfide (2H-MoS ₂). A direct relation between the sliding energy landscape and the corresponding interlayer registry surface of 2H-MoS ₂ is discovered. A simple fit of the model parameters to capture the sliding energy landscape obtained at different external loads enables the identification and isolation of the prominent interlayer interactions dictating the interlayer sliding physics under different tribological scenarios. The success of our method in capturing the results of complex quantum mechanical calculations along with its high computational efficiency marks the RI as a promising tool for studying the tribology of complex nanoscale material interfaces in the wearless friction regime.