Simulation of Hydrogen-Induced Reconstruction of Oxygen on Pd(111)

The oxygen and hydrogen atoms co-adsorption experiment on Pd(111) is modelled using kinetic Monte Carlo method. We consider O-O, H-H, and O-H interactions and several kinetic processes (diffusion, surface and subsurface H-atoms exchange and water-formation reaction) leading to the phase transition $(2×2)_O$ → $(\sqrt(3)×\sqrt(3))_O$ with increase in H-coverage. We also demonstrate how reverse phase transition $(\sqrt(3)×\sqrt(3))_O$ → $(2×2)_O$ occurs due to hydrogen dissolution into subsurface in the absence of hydrogen gas. At higher temperature we observe the disappearance of $(2×2)_O$ oxygen islands due to water-formation reaction.