Present knowledge of the function of materials is largely based on studies (experimental and theoretical) that are performed at low temperatures and ultralow pressures. However, the majority of everyday applications, like, e.g., catalysis, operate at atmospheric pressures and temperatures at or higher than 300 K. Here we employ ab initio, atomistic thermodynamics to construct a phase diagram of surface structures in the $(T,p)$ space from ultrahigh vacuum to technically relevant pressures and temperatures. We emphasize the value of such phase diagrams as well as the importance of the reaction kinetics that may be crucial, e.g., close to phase boundaries.

• Received 16 October 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.046103