Dissociative Chemisorption of O on Al(111): Dynamics on a Correlated Wave-Function-Based Potential Energy Surface.

Dissociative chemisorption of O on the Al(111) surface represents an extensively studied prototype for understanding the interaction between O and metal surfaces. It is well known that the experimentally observed activation barrier for O dissociation is not captured by conventional density functional theory. The interpretation of this barrier as a result of spin transitions along the reaction path has been challenged by recent embedded correlated wave function (ECW) calculations that naturally yield an adiabatic barrier. However, the ECW calculations have been limited to a static analysis of the reaction pathways and have not yet been tested by dynamics simulations. We present a global six-dimensional potential energy surface (PES) for this system parametrized with ECW data points. This new PES provides a reasonable description of the site-specific and orientation-dependent activation barriers. Quasi-classical trajectory calculations on this PES semiquantitatively reproduce both the observed translational energy dependence of the sticking probability and steric effects with aligned O molecules.