Stars and stripes. Nanoscale misfit dislocation patterns on surfaces

Close-packed metal surfaces and heteroepitaxial systems frequently display a structure consisting of regularly spaced misfit dislocations, with a network of domain walls separating face-centered cubic (fcc) and hexagonal close-packed (hcp) domains. These structures can serve as templates for growing regularly spaced arrays of nanoislands. We present a theoretical investigation of the factors controlling the size and shape of the domains, using Pt(111) as a model system. Upon varying the chemical potential, the surface structure changes from being unreconstructed to the honeycomb, wavy triangles, bright stars, or Moire patterns observed experimentally on Pt(111) and other systems. For the particular case of Pt(111), isotropically contracted star-like patterns are favored over uniaxially contracted stripes.