  Molecular dynamics simulations are carried out to investigate the dynamic
behavior of the slip length in thin polymer films confined between atomically
smooth thermal surfaces. For weak wall-fluid interactions, the shear rate
dependence of the slip length acquires a distinct local minimum followed by a
rapid growth at higher shear rates. With increasing fluid density, the position
of the local minimum is shifted to lower shear rates. We found that the ratio
of the shear viscosity to the slip length, which defines the friction
coefficient at the liquid/solid interface, undergoes a transition from a nearly
constant value to the power law decay as a function of the slip velocity. In a
wide range of shear rates and fluid densities, the friction coefficient is
determined by the product of the value of surface induced peak in the structure
factor and the contact density of the first fluid layer near the solid wall.
