Reconstruction of the Fe(110) surface by a quarter monolayer of S was shown by low-energy electron-diffraction intensity analysis to correspond to a model in which hard-sphere atoms displace to a unique jamming point. After reconstruction the S atoms sit in fourfold hollows of touching Fe atoms with S-Fe bond lengths of 2.17 and 2.36Å. A general construction for 2 x 2 reconstructions with rectangular symmetry was given and applied to this case and to Ni(001)(2 x 2)-C.

Metal-Surface Reconstruction Induced by Adsorbate - Fe(110) p(2 x 2)-S. H.D.Shih, F.Jona, D.W.Jepsen, P.M.Marcus: Physical Review Letters, 1981, 46, 731-4