Theoretical simulation of noncontact atomic force microscopy in liquids

Methods of theoretical simulations of noncontact atomic force microscopy in liquids have been developed. Though there are several difficult issues for the theoretical simulations in liquids, the authors introduce here the simulation methods for the cantilever oscillation in liquids and the tip-sample interaction force mediated by water molecules. As for the cantilever motion, a very efficient numerical method is proposed which solves the oscillation of the elastic beam cantilever and fluid dynamics simultaneously. The results reproduce fairly well the resonant curve and related properties of the Si beam cantilever. As for the simulation of the tip-sample interaction force in water, classical molecular dynamics (MD) method is adopted in the present work. The case study by MD for the mica surface in water revealed new features that appeared in the three-dimensional force map.