INVESTIGATION OF THE ATOMIC-SCALE FRICTION AND ENERGY-DISSIPATION IN DIAMOND USING MOLECULAR-DYNAMICS

We have used molecular dynamics simulations to examine friction when t wo diamond (111) surfaces are placed in sliding contact. The essence o f atomic-scale friction was shown to be the mechanical excitation (in the form of vibrational and rotational energy) of the interface lattic e layers upon sliding. This excitation was propagated to the rest of t he lattice, and eventually dissipated as heat. In general, this excita tion increases with increasing applied load; therefore, the atomic-sca le friction also increases with load. Flexible hydrocarbon species, ch emically bound to the diamond surface, can lead to a significant reduc tion of mechanical excitation upon sliding at high loads, leading to l ower friction. In addition to clarifying the effects of chemically-bou nd hydrocarbon groups on atomic-scale friction at diamond interfaces, these simulations might also yield insight into more complicated syste ms, e.g. Langmuir-Blodgett films, and aid in the design of low-frictio n coatings.