Friction phenomena in a two-dimensional Frenkel-Kontorova model

By using the molecular dynamic simulation method with afourth-order Runge--Kutta algorithm, a two-dimensional dc- andac-driven Frenkel--Kontorova (FK) model with a square symmetrysubstrate potential for a square lattice layer has been investigatedin this paper. For this system, the effects of many differentparameters on the average velocity and the static friction forcehave been studied. It is found that not only the amplitude andfrequency of ac-driven force, but also the direction of the externaldriving force and the misfit angle between two layers have somestrong influences on the static friction force. It can be concludedthat the superlubricity phenomenon appears easily with a larger acamplitude and lower ac frequency for some special direction of theexternal force and misfit angle.