It was recalled that room-temperature scanning tunnelling microscopy images frequently showed regions of antisymmetrical dimer-ordering surrounding certain types of defect on the Si(001) surface. While it was generally believed that any defect, asymmetrical with respect to the dimer row, would induce this dimer-pinning effect, recent experimental results had shown that this was not the case. A model was presented, based upon a nearest-neighbor Ising treatment of the surface, which permitted the extent of pinning - caused by a dimer - to be predicted on the basis of ab initio calculations. This model was used to predict the extent of pinning for three P-containing structures, and one of these asymmetrical features was identified as causing no appreciable pinning. In addition, ab initio calculations were used to identify the effects which governed the interaction between neighboring dimers.

Defect-Induced Dimer Pinning on the Si(001) Surface. H.F.Wilson, N.A.Marks, D.R.McKenzie: Surface Science, 2005, 587[3], 185-92