Evidence for strain induced 2D roughening in Ag islands on Pt(111)

By static and molecular dynamics computations with embedded atom potentials we study the influence of strain and temperature on the morphology of low coverage Ag overlayers on Pt(111). Static computations show that strain reduces the contour (Ec) and kink (Eₖ) energies of the Ag islands. Simulations of the short time evolution ({~}10 nsec) after deposition predict that, for T{~}600 K, the low Ec and Eₖ energies result in the roughening of the islands' boundary. This, in turn, leads to easy fragmentation of the islands, and to enhanced Ag mobility on the surface.