First-principles statistical mechanics approach to step decoration at   surfaces
  Using a first-principles parameterized lattice-gas Hamiltonian we study the adsorbate ordering behavior at atomic steps of a Pd(100) surface exposed to an oxygen environment. We identify a wide range of gas-phase conditions comprising near atmospheric pressures and elevated temperatures around 900 K, in which the step is decorated by a characteristic O zigzag arrangement. For catalytic processes like the high-temperature combustion of methane that operate under these conditions our approach thus provides first insight into the structure and composition at a prominent defect on the working surface. 
Yongsheng Zhang (1) and Karsten Reuter (1) ((1) Fritz-Haber-Institut   der Max-Planck-Gesellschaft, Berlin, Germany)