THEORETICAL CALCULATIONS OF COEFFICIENTS OF FRICTION BETWEEN WEAKLY INTERACTING SURFACES

Ab initio molecular orbital calculations were performed to predict the friction force and the coefficient of friction between surfaces conta cted by van der Waals forces. Friction between graphite and a body ter minated by hydrogen atoms was calculated for model systems of a naphth alene/hydrogen molecule and a pyrene/ hydrogen molecule. The calculati ons showed that the friction for this system is isotropic. A coefficie nt of friction of 0.011-0.015 was predicted, which was in agreement wi th values from various friction-force microscope measurements, and was located at the lower limit of the macroscale experimental values. A t heory to account for the calculated microscale friction is presented, and the derived results are compared to the calculated results.