Long-Range Periodicity of S/Au(111) Structures at Low and Intermediate Coverages

Abstract

Through a systematic analysis based on DFT calculations, we have studied the adsorption of S atoms on Au(111) at low and intermediate coverages (θ ≤ 1/3). Our calculations predict ground state structures characterized by two periodicities: (5 × 5) and (√3 × √3)R30°. In line with experiments, the (5 × 5) periodicity seems to dominate in a much larger coverage range than the (√3 × √3)R30° one, which should be only observable in a narrow coverage window close to 1/3. In addition, our results unambiguously reveal the crucial role of S-induced substrate relaxation. Using a firstprinciples parametrized lattice-gas Hamiltonian approach, we determine lateral interactions between S atoms which allow us to provide a sound explanation for the relative stability of ground state structures.