Symmetry and shape of reconstructed two-dimensional islands

Abstract

We show that the symmetry of reconstructed two-dimensional islands on reconstructed surfaces can deviate from both the symmetry of the underlying substrate and the symmetry of the reconstruction. Only an analysis of the symmetry of the combined system of the reconstruction on the substrate and the reconstruction on the island can predict the symmetry of the island shapes (equilibrium shape or steady-state growth shape). We introduce a general method for the symmetry analysis of the combined system which identifies all possible mutual shifts of the reconstruction on island which obey a certain crystal symmetry.