  Using molecular dynamics based on Langevin equations with a coordinate- and
velocity-dependent damping coefficient, we study the frictional properties of a
thin layer of "soft" lubricant (where the interaction within the lubricant is
weaker than the lubricant-substrate interaction) confined between two solids.
At low driving velocities the system demonstrates stick-slip motion. The
lubricant may or may not be melted during sliding, thus exhibiting either the
"liquid sliding" (LS) or the "layer over layer sliding" (LoLS) regimes. The
LoLS regime mainly operates at low sliding velocities. We investigate the
dependence of friction properties on the misfit angle between the sliding
surfaces and calculate the distribution of static frictional thresholds for a
contact of polycrystalline surfaces.
