The room-temperature oxygen-induced (2 x 2)p4g clock reconstruction of Rh(001) was investigated by low-energy alkali ion scattering, recoiling spectrometry, low-energy electron diffraction, and three-dimensional classical scattering simulations. The oxygen atoms were confirmed to be in the fourfold hollow sites to produce the glide plane symmetry of the substrate observed in the low-energy electron diffraction pattern. Quantitative values for the geometrical parameters were obtained by using a reliability R-factor analysis to compare the experimental and simulated azimuthal scans. The lateral clockwise-counterclockwise displacement of the surface rhodium atoms was Δx = 0.2Å and the oxygen height above the substrate was Δh = 0.6Å. The driving force for this clock reconstruction was discussed and compared with previous results on the Ni(001)-(2 x 2)p4g-C surface.

Oxygen-Induced Surface (2 x 2)p4g Reconstruction of Rh(001). Y.G.Shen, A.Qayyum, D.J.O'Connor, B.V.King: Physical Review B, 1998, 58, 10025-30