Surface relaxations, current enhancements, and absolute distances in high resolution scanning tunneling microscopy - art. no. 236104

We have performed the most realistic simulation to date of the operation of a scanning tunneling microscope. Probe-sample distances from beyond tunnel ing to actual surface contact are covered. We simultaneously calculate forc es, atomic displacements, and tunneling currents, allowing quantitative com parison with experimental values. A distance regime below which the probe b ecomes unstable is identified. It is shown that the real distance differs s ubstantially from previous estimates because of large atomic displacements on the surface and at the probe tip.