Topographic images.

In reflecting on the simulations and the gradual resolution of the puzzle, it becomes clear that only a very limited part of the whole physical situation is actually accessible in the experiments. The change of the position of the SPM tip is a result of measurements of constant-current/height contours. But the change of the position of surface atoms under given experimental conditions cannot be determined. This makes simulations the only source of information on both the stability of a system under specific conditions determined from interaction energies, the elastic limit of a surface and tip system, and the relation between true surface properties (properties of its ground state) and virtual properties that are due to the measurement itself. It might seem that the last distinction is far-fetched. But one only has to consider that atomic positions on a surface can be determined by a number of different methods, e.g., electron diffraction, photon diffraction, and electron tunneling, to understand that different experimental methods might lead to different results. And in this case, the possibility in theory to switch on or off a particular effect makes it quite adaptable to a whole range of experimental data. This becomes even more important in the case of SFM. [ABSTRACT FROM AUTHOR]