Atomistic simulations of the adhesion hysteresis mechanism of atomic scale dissipation innon-contact atomic force microscopy

Abstract

A possible mechanism of atomic scale dissipation in non-contact atomic force microscopy(NC-AFM) is investigated using a non-equilibrium classical molecular dynamicssimulation method with stochastic boundary conditions. We find that for simple flatcrystal surfaces, such as the MgO(001) which does not possess intrinsic surface softvibrational modes, dissipation effects can be explained by tip induced soft modesassociated with well-known atomic instabilities produced by the approaching tip.Extrapolating results of calculations performed for a succession of tip oscillationfrequencies, we suggest that dissipation energies can be obtained via this mechanismwhich are of the same order of magnitude of experimentally observed contrasts.