Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 88: Frontiers of Electronic Structure Theory: Focus on Topology and Transport V
O 88.11: Vortrag
Donnerstag, 10. März 2016, 17:30–17:45, H24
Layer-resolved calculated vibrations at gold surfaces — •Andrei Postnikov1 and Kamil Moldosanov2 — 1Université de Lorraine, LCP-A2MC, Metz, France — 2Kyrgyz-Russian Slavic University, Bishkek, Kyrgyzstan
Vibration modes at (001), (011) and (111) surface of gold are calculated from first principles, using the Siesta method [1] and the frozen phonon approach. Calculations are done on thick slabs of moderate lateral size – (2×2) for (001), (2×3) for (011), (3×3) for (111). This allows to resolve the vibration patterns layer by layer into the depth, in dependence on the in-plane wavevector component, and discriminating the polarisation of vibration modes. One notes the softening of modes at the surface, and an appearance of specifically surfacial modes. The bulk behaviour is largely recovered from the 5th or 6th layer downwards.
This study was driven by an intention to grasp the properties of longitudinal acoustic modes propagating at some depth under the surface of gold nanoparticles, which were an important element of our recent work related to the mechanism of radiofrequency absorption and hence resulting heating of nanoparticles of ≳ 5 nm size [2]. Since it is difficult to meaningfully incorporate the diversity of the nanoparticles’ shapes in a practical calculation, the vibrations beneath the most common facets occurring at the nanoparticles’ surface were studied instead.
1. The Siesta method, http://departments.icmab.es/leem/siesta/ .
2. A. Postnikov and K. Moldosanov, http://arxiv.org/abs/1508.00735 .