Percolation of hydrogen atoms adsorbed on Cu(100) surfaces: DFT, Monte Carlo and finite size scaling techniques

Abstract

Hydrogen adsorption on Cu(100) surfaces was studied taking into account percolation problem. In order to represent the real system, DFT calculations were perfomed to calculate adsorption energies of a hydrogen atom in different environments, according to the number of first neighbours present at each adsorption site. This information was employed in canonical and grand canonical Monte Carlo simulations and the percolation threshold was calculated for different temperatures. A phase diagram which separates percolating and non percolating regions was obtained. Critical exponents were also calculated in order to study the universality of the system. At temperatures below 200K, a particular and interesting behavior was observed, which is evidenced by the results obtained for the isotherms, phase diagram and critical exponents. At higher temperatures, the behavior observed for percolating properties is that expected for repulsive interactions between neighboring adsorbed hydrogen atoms.