title: Two-dimensional roughening of adsorbate islands in thermodynamic equilibrium.
abstract: Equilibrium fluctuations of islands of adsorbed O atoms on Ru(0001) were investigated by scanning tunneling microscopy (STM), density functional theory calculations (DFT) and Monte Carlo (MC) simulations. Very ramified (2 x 2)-O islands were observed by high-speed STM that point to complex interactions between the O atoms. The DFT calculations show that, in addition to pairwise attractive interactions between third-nearest neighbors, a repulsive three-body interaction exists between these. MC simulations that include three-body interactions reproduce the observed ordering behavior.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, and Ludwig-Maximilians-Universität, 80331 München, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wintterlin
authors.forename: J
authors.initials: J
authors.lastname: Trost
authors.forename: R
authors.initials: R
authors.lastname: Schuster
authors.forename: A
authors.initials: A
authors.lastname: Eichler
authors.forename: J-S
authors.initials: JS
authors.lastname: McEwen