Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 14: Surface Chemical Dynamics

O 14.1: Vortrag

Montag, 7. März 2016, 15:00–15:15, S053

The Importance of Meta-Stable Structures and High Spin States for Oxygen Activation on Small Gas-Phase Silver Clusters from First Principles — •Weiqi Wang, Luca M. Ghiringhelli, and Matthias Scheffler — Fritz-Haber-Institut der MPG, Berlin.

At finite temperature, the silver-cluster catalysts could have transient meta-stable structures with spin states higher than those of zero kelvin stable structures (singlets for an even number of silver atoms). These transient structures could be crucial in activating adsorbed species like O₂. In this work, the temperature-dependent relative stability of Ag_n and Ag_nO₂ (n=4,8) systems are simulated at different finite temperatures, by means of replica-exchange ab initio molecular dynamics (REMD) and efficient Boltzmann-reweighting based methods (e.g., Weighted Histogram Analysis Method, WHAM, and multi-state Bennett acceptance ratio estimator, MBAR). The multi-spin-state free energy surfaces are visualised with the help of Sketch-Map [1]. The results show that meta-stable structures and the spin-polarized states can synergistically influence the activation of the adsorbed O₂ molecule. [1] M. Ceriotti, G. A. Tribello, M. Parrinello, J. Chem. Theory Comput. 9, 1521 (2013)