Surface corrugations and layer thickness dependent frictional behavior of MoS₂ – A computational study

2D materials are at the core of nano/micro-electro-mechanical systems (MEMS/NEMS). However, surface corrugations are unavoidable in 2D materials because of operational inefficiencies involved in the synthesis procedures. So far, most related works focus on single planar 2D materials, i.e., Graphene. The existing Transient Metal Dichalcogenide (TMD) analyses do not include torque implications on the frictional force and different variables simultaneously. In this work, we have combined the two aspects, i.e., surface irregularities with the need for tuning the mechanical properties. We have studied tuning the frictional properties of Molybdenum Disulfide (MoS₂) by probing it with reactive molecular dynamics (rMD) modeling, which is further analyzed by density functional theory (DFT) code. We analyzed BADER charge and molecular orbitals by DFT code. We considered multiple cases, i.e., varying number of the layers (1-3), the number of dents (2-8), the radius of each dent (12-24 Å), and the pattern of the dents (in-line and zigzag). We hypothesize the frictional force experienced by the probe is affected by the substrate's geometry, both adjacent to and along the line of contact of probe. The torque plots validate our hypothesis. This approach is useful for any other 2D materials.