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Boundary friction on molecular lubricants: rolling mode?

“…[4]. The equilibrium distance for Lennard-Jonnes interaction (1) is taken equal to the interatomic distance in the solids: r 0 = a.…”

“…The adiabatic treatment of the system, corresponding to the expression (2), follows the lines suggested in Ref. [4]. The equilibrium distance for Lennard-Jonnes interaction (1) is taken equal to the interatomic distance in the solids: r 0 = a.…”

“…The principal physical picture, usually considered in relation with boundary friction on few molecular layers of lubricant liquid, is the sequence of "freezing-melting" processes on the lubricant, giving rise to discontinious (stickand-slip) displacement of sliding surfaces [3]. Recently a new theoretical approach was proposed for microscopic sliding processes at extremely low velocities of motion and upon a monolayer of lubricant atoms [4], as can be the case for friction force microscopy (FFM). Based on the adiabatic formation of metastable states (similar to dislocations in usual deformed crystals or defects in the Frenkel-Kontorova model [5], [6]) and their following relaxation, this treatment shows how the (average) microscopic friction coefficient depends upon the material parameters of the contacting solids and lubricants and also how stick-and-slip jumps with atomic periodicity can develop in the microscopic friction force.…”