Structure-dependent vibrational properties of metallic nanoclusters
Research Center of Laser Fusion, China Academy of Engineering Physics - P. O. Box 919-987, 621900 Mianyang, China
Received: 23 November 2012
Accepted: 29 January 2013
The thermally vibrational properties of icosahedral (ICH) and face-center-cubic (FCC) copper nanoclusters have been compared by carrying out molecular dynamics simulations with a local-environment-dependent tight-binding potential. Although both ICH and FCC copper nanoclusters exhibit a low- and high-energy enhancement of vibrational density of states (VDOS) in comparison with the bulk copper, the vibrational properties of nanoclusters show a strong structure-dependent feature. The different structure is revealed to result in the different atom package, the different lattice shrinkage, the different local pressure, and thus the different VDOS. The different atom package at the surfaces of clusters is responsible for the different low-energy VDOS in a different power-law behavior between the FCC and ICH clusters. The lattice contraction and the internal pressure in the sense of the bulk are unified to explain the enhanced high-energy tail in the VDOS of FCC clusters, but not in the case of ICH clusters.
PACS: 63.22.Kn – Clusters and nanocrystals / 61.46.Bc – Structure of clusters (e.g., metcars; not fragments of crystals; free or loosely aggregated or loosely attached to a substrate) / 68.35.Ja – Surface and interface dynamics and vibrations
© EPLA, 2013