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arXiv · 1811.08062

Two-to-three dimensional transition in neutral gold clusters: the crucial role of van der Waals interactions and temperature

Bryan R. Goldsmith·Jacob Florian·Jin-Xun Liu·Philipp Gruene·Jonathan T. Lyon·David M. Rayner·André Fielicke·Matthias Scheffler·Luca M. Ghiringhelli
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Abstract

We predict the structures of neutral gas-phase gold clusters ($Au_n$, $n$ = 5$-$13) at finite temperatures based on free-energy calculations obtained by replica-exchange ab initio molecular dynamics. The structures of neutral $Au_5$$-$$Au_{13}$ clusters are assigned at 100 K based on a comparison of experimental far-infrared multiple photon dissociation spectra performed on Kr-tagged gold clusters with theoretical anharmonic IR spectra and free-energy calculations. The critical gold cluster size where the most stable isomer changes from planar to nonplanar is $Au_{11}$ (capped-trigonal prism, $D_{3h}$) at 100 K. However, at 300 K (i.e., room temperature), planar and nonplanar isomers may coexist even for $Au_8$, $Au_9$, and $Au_{10}$ clusters. Density-functional theory exchange-correlation functionals within the generalized gradient or hybrid approximation must be corrected for long-range van der Waals interactions to accurately predict relative gold cluster isomer stabilities. Our work gives insight into the stable structures of gas-phase gold clusters by highlighting the impact of temperature, and therefore the importance of free-energy over total energy studies, and long-range van der Waals interactions on gold cluster stability.

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Bryan R. Goldsmith, Jacob Florian, Jin-Xun Liu, Philipp Gruene, Jonathan T. Lyon, David M. Rayner, André Fielicke, Matthias Scheffler, Luca M. Ghiringhelli. 2018-11-20. Two-to-three dimensional transition in neutral gold clusters: the crucial role of van der Waals interactions and temperature. https://doi.org/10.1103/physrevmaterials.3.016002

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