Molecular simulations have been used to study the behaviors of lubricants in an ultra thin film lubrication. The very small part of lubrication surface has been modeled in conventional molecular calculations. In this study, we modeled the whole of lubrication surface including the inlet and outlet of lubricant at lubrication region. The lubricating mechanisms such as squeeze action and wedge action and the effects of the interaction between solid and lubricant on lubrication properties were examined by the calculations using molecular models. The results of the calculations shows that the squeeze and wedge action generates the pressure at lubrication region, which is similar to the results from a classical continuum theory of lubrication. This implies that the mechanism of a nano-lubrication is the same as that of a macroscopic lubrication. From the results of the solid-liquid interaction calculations, it is showed that the slip between solid and liquid interaction leads to low friction in a shear.
