Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 16: Heterogeneous Catalysis: Theory
O 16.4: Vortrag
Montag, 12. März 2018, 15:45–16:00, MA 141
Finite-Temperture Statistical Study of Small Silver Clusters Agn (n= 4-13) interacting with O2 molecules — •Weiqi Wang and Luca M. Ghiringhelli — Fritz-Haber-Institut der MPG, Berlin
Due to their unique physical and chemical properties, noble-metal clusters have attracted tremendous interest in recent decades. In this work, we systematically study both the static and the dynamical properties at finite temperature of sub-nanometer-sized neutral silver clusters Agn (n= 4-13), with and without adsorbed O2, in order to reveal correlations between the structure, the local charge, and the bond dynamics.
Clusters with different (fixed) spin states are sampled at different temperatures by replica-exchange ab initio molecular dynamics, where the forces bewteen atoms are described via density-functional theory.
Regarding dynamical properties, we focus our attention on the bond life-time, studied by means of the bond auto-correlation function.
Interestingly, we find a correlation between the local charge state of bonded atom pairs, estimated via the Hirschfeld charge partitioning, and the bond life-time. In particular, negatively charged Ag binded pairs (with elongated Ag–Ag bond) tend to have shorter bond life times. Since O2 molecules tend to adsorb onto these negatively charged sites, the O–O bond gets activated upon adsorption. This suggests that the local charge may be a good descriptor for the identification of active sites on the nanoclusters.