A study was made of the effect of an idealized tip-induced electric field upon the electronic structure of a semiconductor surface which contained defects. The embedding-potential method was used to connect the Green’s functions of the solid and the vacuum. The corresponding localized perturbation potential permitted the derivation of the Dyson equation for the Green’s function of the full system. This equation was solved, in real space, on a discrete mesh. Polarization of the defective surface was determined within the tunnelling barrier. It was found that the electronic density over the clean surface responded more strongly to the tip-induced electric field than did the electronic density over regions which contained defects.

H.Ness, A.J.Fisher: Journal of Physics - Condensed Matter, 1997, 9[8], 1793-811