Molecular dynamics simulation of friction on the atomic scale

Several molecular dynamics simulations are performed, in order to clarify the atomic-scale stick-slip phenomenon which is commonly observed in the surface measurement using an atomic fine microscope (AFM). In the molecular dynamics simulations, a specimen and a slider are assumed to consist of monocrystalline copper and rigid diamond, respectively, and a Morse potential is postulated between a pair of atoms. Atomic behavior in a plane corresponding to the (111) crystal plane is simulated, dealing with a planar strain problem where the effect of the three-dimensional interatomic force and the spring constant of the AFM cantilever are also taken into consideration. Influence of the cantilever stiffness and dynamics of the specimen surface atoms on the atomic-scale stick-slip phenomenon are investigated. The simulation confirms that the atomic-scale stick-slip phenomenon can be expressed by a molecular dynamics simulation and that the stick-slip phenomenon of the surface atoms of the specimen affects the stick-slip phenomenon of the spring force. These results indicate that molecular dynamics simulation has an advantage in deciding the spring constant of cantilevers.