Molecular dynamics simulations of friction between an ordered organic monolayer and a rigid slider with an atomic-scale protuberance

The atomic-scale friction between an ordered organic monolayer and a rigid probing slider with an atomic-scale protuberance was investigated using a m olecular dynamics method. The slider was used to model the tip apex used in atomic force microscopy. In order to control the normal load, three orthog onal springs and a feedback regulation unit were introduced. The protuberan ce, composed of a small number of atoms, brought about local and collective deformation of the monolayer and generated a friction force. Various frict ional properties were investigated in terms of the size of the protuberance , the length of molecules in the monolayer, and the conditions, such as tem perature, applied normal load, and some parameters of the external observat ion system. Lattice-resolved friction signals were obtained when the size o f the protuberance was comparable to the cross-sectional area of the molecu le.