Monte Carlo simulations and Cluster-exact Approximation applied to H/Cu(100), H/Ag(100) and O/Cu(100) systems

SANCHEZ VARRETTI F. O.; GOMEZ E. DEL V.; AVALLE L.B.; BULNES F. M.; GIMENEZ M.C.; RAMIREZ-PASTOR A. J.

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2019

0169-4332

AbstractThe systems H=Cu(100), H=Ag(100) and O=Cu(100) were analyzedtheoretically by means of DFT calculations, Monte Carlo (MC) simu-lations and a Cluster-exact (CA) Approximation. To model these realsystems, a two stages procedure was used. In a rst stage, DFT cal-culations were performed in order to determine the adsorption energiescorresponding to a hydrogen or oxygen atom in dierent environments.The obtained values depend on the number of rst neighbors present ineach adsorption site. For the systems H=Cu(100) and O=Cu(100), lateralinteractions between adatoms were found to be repulsive, while for theH=Ag(100) system, the interactions are attractive, except for the case offour nearest neighbours. Then, with this information, MC simulationsand CA approximation were applied for dierent temperatures. The pro-cess was monitored by following the surface coverage as a function of thechemical potential (adsorption isotherm). Interesting behaviors were ob-served and discussed in terms of the low-temperature phases formed inthe adsorbed layer. In addition, a good agreement was found betweenMC and CA results, especially at high temperatures. At low tempera-tures, a chessboard-like phase was observed for the systems H=Cu(100)and O=Cu(100).