  We performed atomic and electron dynamics analysis to study the impact of
morphological and thickness changes of a MoS2 system on its tribological
properties through a diamond tip. We had considered 4 cases: variable layers
(1-4 layers) and number (2-8 indents), radius (12{\AA}, 16{\AA}, 20{\AA},
24{\AA}), and pattern of indents (0{\deg}, 25{\deg}, 30{\deg}, 35{\deg},
45{\deg}, 60{\deg}) resulting into 18 subcases. MD results showed changing the
radius and number of indents were the most, and number of layers and indents'
pattern were the least effective way to tune the frictional characteristics.
Ground state ab-initio study demonstrated an increase in the number and radius
of indents, raising the number of stretched bonds. Consequently, the volume
covered by the HOMO iso-surface increases, and that of LUMO decreases. That
makes higher area/volume available to lose/share electrons, resulting in
stronger interlocking between layers and tip. And TD-DFT calculation proves the
existence of interfacial excitons, resulting in stronger interlocking between
the layer's surface and tip despite a contraction in the LUMO iso-surfaces'
area/volume. We believe these interlayer excitons result in higher average
Z-axis(hence frictional force) reaction forces for the indents number subcases
and lower for indents radius subcases as the number and radius of indents
increase.
