The Reconstruction of Pt(111) and Domain Patterns on Close-packed Metal Surfaces

We have studied the reconstruction of Pt(111) theoretically using a two-dimensional Frenkel-Kontorova model for which all parameters have been obtained from ab initio calculations. We find that the unreconstructed surface lies right at the stability boundary, and thus it is relatively easy to induce the surface to reconstruct into a pattern of FCC and HCP domains, as has been shown experimentally. The top layer is very slightly rotated relative to the substrate, resulting in the formation of "rotors" at intersections of domain walls. The size and shape of domains is very sensitive to the density in the top layer, the chemical potential, and the angle of rotation, with a smooth and continuous transition from the honeycomb pattern to a Moire pattern, via interlocking triangles and bright stars. Our results show clearly that the domain patterns found on several close-packed metal surfaces are related and topologically equivalent.