Surface phase transitions at O and CO catalytic reaction on Pd(1 1 1)

The model has been proposed to simulate numerically the reaction O + CO → CO2 and occurring phase transitions on Pd(1 1 1) surface. We calculate the phase diagram for this system by kinetic Monte Carlo method. It shows the phase transitions image and image with increase of CO coverage for room and intermediate temperatures, respectively, while in the low temperature limit the direct p(2 × 2)O → p(2 × 1)O phase transition is observed. We demonstrate that the reaction rate is the crucial factor determining the occurrence of the p(2 × 1)O phase and vanishing of the image with decrease of temperature. The results indicate that the reaction proceeds inside both the p(2 × 2)O and image phases, but on the perimeter of the domains of p(2 × 1)O structure.