Low-energy electron diffraction analyses of several structure models for the Ge(001) 2 x 1 surface confirm that the reconstruction involves at least 3 layers, and demonstrate that models with buckled asymmetric dimers were favoured over models with symmetric dimers. Three models with different amounts of buckling were given, which show equivalent moderate agreement with experiment.

The 2 x 1 Reconstruction of the Ge(001) Surface. J.C.Fernandez, W.S.Yang, H.D.Shih, F.Jona, D.W.Jepsen, P.M.Marcus: Journal of Physics C, 1981, 14, L55-60