Simulating dynamic force microscopy imaging of a NaCl island using non-ideal tips

We use atomistic simulation to study how the contrast pattern in dynamic force microscopy depends on the structure of the tip. Using a NaCl island on the NaCl(001) surface as a template, we consider several different NaCl tip configurations, with and without OH contamination. We find that the most significant changes in images are produced by very soft tips, which demonstrate large relaxations due to tip-surface interaction. Harder tips produce qualitatively similar images regardless of the atomic configuration presented to the surface. Contamination of the tip by hydroxyl groups reduces the strength of the interaction, and, in certain configurations, can produce asymmetries in the image even on the flat terrace of the island.