The missing-row model for the reconstructed Pt(110)−(1 × 2) surface: A leed intensity analysis showing multilayer distortions

The (1 × 2) missing-row reconstruction of clean Pt(110) is studied with a new low-energy electron diffraction (LEED) intensity analysis. In order to obtain theoretical intensity-voltage curves in good agreement with experiment, it is necessary to consider distortions from the basic missing-row model in the theoretical treatment. In our calculations, alternating row-pairing and vertical buckling distortions down to the fourth layer are allowed for the first time. Large contractions are seen in the first three layer spacings, and significant distortions are found even in the fourth layer. The distortions are similar to those seen in Ir and Au LEED results as well as those predicted by the embedded atom method (EAM) for Pt. In the optimum geometry, the top-layer spacing contracts by 18%. The atoms in the second layer pair towards the missing rows, in agreement with Ir and Au LEED but in the direction opposite to that predicted by EAM. The R-factors are especially sensitive to the third-layer buckling. The fourth-layer pairing is also towards the missing rows, in agreement with the EAM prediction. It is shown that full dynamical LEED calculations of this kind can be realistically run on a personal computer with suitable coprocessor board.