Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 39: Computational Materials Modelling V
MM 39.4: Vortrag
Donnerstag, 17. März 2011, 17:00–17:15, IFW A
(contribution withdrawn) Superheating Gallium Clusters — •Nicola Gaston1 and Krista G. Steenbergen2 — 1MacDiarmid Institute, IRL, Wellington, New Zealand — 2Victoria University Wellington, New Zealand
The experimental discovery of superheating in gallium clusters [1] contradicted the clear and well-demonstrated paradigm that the melting temperature of a particle should decrease with its size [2]. However the extremely sensitive dependence of melting temperature on size also goes to the heart of cluster science, and the interplay between the effects of electronic and geometric structure [3]. In the case of gallium, the extreme polymorphism displayed by the bulk metal introduces additional complications. We use our understanding of the dimeric bulk structure of gallium to elucidate the patterns of bonding in the clusters, which also display dimeric structural motifs for small sizes. In particular, the deviation of gallium from the extremely general linear relationship of melting temperature and cohesive energy for elemental solids demonstrates that the low melting temperature of gallium corresponds to the melting of a molecular solid. We present systematic calculations of the melting-like transition in small gallium clusters, and a comparison with aluminium clusters of similar sizes. Finally, we discuss the importance of features of the electronic structure for the melting-like transition.
[1] G. A. Breaux, R. C. Benirschke, T. Sugai, B. S. Kinnear, and M. F. Jarrold, Phys. Rev. Lett. 91, 215508 (2003) [2]P. Pawlow, Z. Phys. Chem. 65, 1 (1909) [3]M. Schmidt, R. Kusche, B. von Issendorff, and H. Haberland, Nature 393, 238 (1998)i