Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 31: Heterogeneous Catalysis: Theory
O 31.9: Vortrag
Dienstag, 8. März 2016, 12:30–12:45, S053
(Meta)stability and Dynamics of Nanoclusters at Finite-Temperature — •Diego Guedes-Sobrinho1, Juarez L. F. Da Silva1, Ian Hamilton2, and Luca Ghiringhelli3 — 1University of Sao Paulo, Sao Carlos, Brazil — 2Wilfrid Laurier University, Waterloo, Ontario, Canada — 3Fritz Haber Institut der MPG, Berlin, Germany
Due to their catalytic properties, transition-metal nanoclusters have been the focus of a large number of experimental and theoretical studies. However, an atomistic understanding of the temperature effects on their structure are far from satisfactory. In this work, we investigate the (meta)stability and dynamics of Au nanoclusters in a range of sizes where a core-shell structure starts to be formed, namely in the range from 25 to 40 atoms. We use ab initio molecular dynamics combined with replica-exchange techniques, in order to obtain an unbiased statistical sampling of the phase space. The energy and forces are described via the PBE exchange-correlation functional, including many-body dispersion interactions [1], as implemented in the all-electron, full potential, numeric atom-centered orbital based FHI-aims package. We find that at room and higher temperature, the gold clusters at the chosen sizes exhibit a dynamical core-shell structure, with a (typically) tetrahedral core loosely bound to the outer liquid-like shell. A suitable structural descriptor, based on the radial distribution function referred to the cluster’s center-of-mass, is introduced, in order to capture the invariants along the dynamics of these structures. [1] A. Tkatchenko et al., J. Chem. Phys., 138, 074106 (2013).