The structures of 2 reconstructed phases on the (100) surface were studied by means of high-resolution He diffraction. It was shown that, in both cases, the superstructure in the approximate <011> direction was not five-fold but much larger. However, the mean distance between atomic rows in the top layer was very close to that of a five-fold superstructure. This supported the description of the surface layer in a model which assumed static oscillations about a flat and equidistant atom arrangement.

K.Kuhnke, K.Kern, G.Comsa, W.Moritz: Physical Review B, 1992, 45[24], 14388-91