title: Exploring the T-Θ phase diagram of S adsorbed on Au(111) substrate on the Θ = 0.5 ML line.
abstract: Theoretical results for the adsorption of half of a monolayer of S on Au(111) are presented. The simulations were made using a density functional theory (DFT) tight binding approach combined with classical molecular dynamics at 800, 500, 300, 150 and 1 K. By considering a minimal (2 × √3) unit cell, two stable adsorbed phases are found: a dimeric one and another forming a rhomboidal structure depending on the preparation of the sample at high temperatures. Optimized calculations at T = 0 K indicate that the stability of the dimeric phase is due to the increase of the binding energies between sulfur atoms. Enforcing previous results (Gómez-Carrillo et al 2011 Phys. Chem. Chem. Phys. 13 461) it is verified that at high temperatures (T > 300 K) sulfur atoms have a high mobility which allows migration among different adsorption sites. The mobility decreases with the temperature and, as in the previous work, a thermal barrier of 25-30 meV is found. On enlarging the unit cell new agglomerates are found, in good agreement with experimental data.
authors.affiliation: Departamento de Física, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829 S3000AOM Santa Fe, Argentina. scgomez@fiq.unl.edu.ar
authors.forename: S C
authors.initials: SC
authors.lastname: Gómez-Carrillo
authors.forename: P G
authors.initials: PG
authors.lastname: Bolcatto
mesh_terms: D000327:Adsorption; D016000:Cluster Analysis; D003198:Computer Simulation; D006046:Gold / Q000737:chemistry*; D006358:Hot Temperature; D008962:Models, Theoretical; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D013455:Sulfur / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D013455:Sulfur; D006046:Gold