Scanning Tunnel Microscopy Surface State Electron Scattering: Two-Tip Results from One-Tip Data

The scanning tunneling microscopy experiments have opened up a new class of scattering inversion problems, where the scatterers are fixed and the boundary condition corresponds to a movable point source. Using a least square method, we can obtain the scattering T-matrix for an assembly of atoms (s-wave point scatterers) on a surface; and thus the off-diagonal elements of the Green function just from the knowledge of the one-tip data. Therefore, transport property measurements such as that suggested by Niu et al., which are needed when other kind of defects are present, can be predicted solely from the one-tip data.