Clusters and Surfaces in Reactive Atmospheres at Realistic Conditions: Beyond the Static, Monostructure Description*

The processes occurring at surfaces play a critical role in the manufacture and performance of advanced materials, e.g., electronic, magnetic, and optical devices, sensors, and catalysts. A prerequisite for analyzing and understanding the electronic properties and the function of surfaces is detailed knowledge of the atomic structure, i.e., the surface composition and geometry under realistic gas-phase conditions. The key quantity for studying the structure and function of surfaces/clusters in reactive atmospheres is the Gibbs free energy, as function of number of particles, pressure, and temperature. Here, I present a set of methods for the sampling of the configurational space of (nano)clusters and surfaces in reactive (e.g., O2, H2) atmosphere, in the canonical and grand-canonical ensembles, aiming at the unbiased determination of the phase diagrams as function of temperature and partial pressure of the reactive gas.
Applications to gold and metal-oxide nanoclusters, and silicon surfaces, described with first-principles potential-energy surfaces, will demonstrate the insight gained by the direct access to observables at finite temperature and pressure.