First-principles theory of atom extraction by scanning tunneling microscopy.

A new method to provide a self-consistent electronic structure, field, and current distribution for an atomistic bielectrode system with applied bias voltages is presented. In our method the scattering waves are calculated by a step-by-step recursion-matrix method and two different Fermi levels are assigned to each electrode in accord with a given applied bias voltage. The method is applied to the scanning tunneling microscope (STM) system around the contact region. The tip-surface chemical interaction induced by the electric fields is shown to be important for the extreme specificity of atom extraction by STM.