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.

Geometries and Interaction Energies of Toluene on CsxNa1–xMordenite

“…The tolerance criteria for convergence were 10 −4 eV atom −1 for the total energy of the primitive cell. The numerical error of the calculation was ≈10 meV . The vdW corrections according to Grimme's DFT‐D3 were used throughout all periodic calculations …”

“…The numerical error of the calculation was %10 meV. [40,41] The vdW corrections according to Grimme's DFT-D3 were used throughout all periodic calculations. [35] The efficiency and robustness of results arising from the approaches implemented in the fireball code had been validated by hundreds of articles along the last decades.…”

“…A more realistic estimation is to perform a Boltzmann-weighted average. This alternative means to combine DFT calculations with molecular dynamics (MD) [40,41] or Monte Carlo [42] to incorporate temperature effects. Despite that this is not the scope of this particular analysis, a preliminary DFT-MD can be reported.…”