It was recalled that most of the techniques which were used to determine the structure of reconstructed surfaces were relatively insensitive to displacements which were perpendicular to the surface; especially those of sub-surface atoms. It was noted that reflection high-energy electron diffraction was sensitive to such displacements. A dynamic simulation of reflection high-energy electron diffraction intensities was carried out here and it was shown that, in the case of the Si(111) 7 x 7 reconstruction, the dimer-adatom stacking-fault model, optimized by using ab initio parallel computation, provided more accurate atomic positions than had previous determinations involving other approaches. This suggested that the relative intensities of reflections in a reflection high-energy electron diffraction pattern contained sensitive surface structural information.

Y.Ma, S.Lordi, J.A.Eades, S.Ino: Physical Review B, 1994, 49[24], 17448-51