Bringing Theory to Experiment in SFM

6.5 Summary

In this chapter we have shown how theorists actually proceed from a given SFM experimental result to arrive at a realistic simulation of the imaging process. It turned out that the key to successful modeling lies in the ability to successively refine the theoretical model, especially with regard to allowing flexibility in tip selection. This process is inherently iterative: it is usually not possible to arrive at a consistent model that agrees with experimental data without several iteration cycles to fine-tune the model. Contrary to what one might believe, theoretical modelling of SFM experiments is therefore no black box, at least not at the present stage. A general approach for real understanding in SFM simulations must include the following components:

• Justification for the interaction simulation method itself: empirical potentials can be useful, but must be carefully tested, and are usually inflexible.

• An attempt to model the real experimental tip if enough data exists, or at least several plausible models must be considered.

• For high-resolution imaging, tip and surface relaxations must be included since they have a significant influence on the interactions.

• The dynamics of the cantilever and experimental electronics must be treated at a level appropriate for the phenomenon being simulated.