Adsorption of Metals on (100) Metallic Surfaces: Monte Carlo Simulations and Geometrical Phase Transitions

Adsorption and continuous phase transitions (percolation) of metals on (100) metallic surfaces are studied by means of Monte Carlo simulations and the finite-size scaling theory. The studied systems are Ag/Au(100), Au/Ag(100), Ag/Pt(100), and Pt/Ag(100), and the embedded atom method (EAM) is employed for energy calculations. Pairwise interactions are also considered for comparative purposes. The study of critical exponents reveals that these systems belong to the same universality as random sequential adsorption (RSA). For the four systems studied, and the two kinds of interactions considered, phase diagrams of percolation threshold, θ_c, as a function of temperature are presented. In all cases, and for all temperatures, θ_c is always below the value corresponding to RSA, as expected for attractive interactions, and it tends to that value as T → ∞. At intermediate temperatures, a particular behavior is found for EAM interactions.