Im Ionel Ciobica

The dynamic interaction of Co with Ru(0001) in the presence of adsorbed Co and hydrogen

This study deals with the dynamic interaction of CO with the bare Ru(0001), the fully hydrogen- and fully CO-covered ruthenium surface. Molecular beam techniques are applied to investigate the potential energy surface of the ruthenium CO interaction and the chemically modified surfaces. The clean surface shows all properties of a deep uniform chemisorption well with a strong rotational anisotropy. The strong chemically attractive interaction can be diminished by CO adsorption, which leads to zero sticking, even at translational energies as high as 1.2 eV. The angular distribution shows a substantial broadening compared to the clean surface. As shown recently, in the case of hydrogen, CO adsorption turns into an activated process with the atop position being the only available adsorption site. Scattering CO molecules from the hydrogen-covered surface leads to very narrow angular distributions. The collisions are mainly quasi-elastic.

From DFT Calculations to Dynamic Monte Carlo Simulations. The reactivity of CHX on the Ru(0001) Surface

Abstract The dissociation of methane and hydrogenation of atomic carbon on the Ru(0001) surface are simulated via the Dynamic Monte Carlo method. First-principle quantum chemical calculations are carried out to predict the binding energies and lateral interactions of adsorbed CH X species on the Ru(0001) surface. Subsequently, the DFT results are used to parametrise the interactions of these adsorbates on the surfaces. The lateral interactions are assumed to be pairwise additive. The DMC with lateral interaction is compared to a classical Mean Field description and DMC without lateral interactions. The inclusion of lateral interactions induces a radical change to the behavior of the simulation with an increase of the rate of dissociation while the rate of hydrogenation decreases.