Oblate equilibrium shapes of hemispheroidal atomic clustersD. N. Poenaru1, 2, R. A. Gherghescu1, 2, A. V. Solov'yov1 and W. Greiner1
1 Frankfurt Institute for Advanced Studies (FIAS), J. W. Goethe Universität - Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main, Germany, EU
2 Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) RO-077125 Bucharest-Magurele, Romania, EU
received 8 July 2009; accepted in final form 7 October 2009; published October 2009
published online 4 November 2009
The experimentally observed oblate equilibrium shapes of deposited atomic clusters are explained by simulating the interaction energy with the substrate. The surface tension on the contact area is multiplied with a factor, i, taking values in the interval (-1.98, 2). Minimization of the liquid-drop deformation energy of a sodium cluster allows to obtain a wide range of equilibrium shapes: hyperdeformed oblate hemispheroid (deformation = -1); superdeformed oblate hemispheroid ( = -0.68); hemisphere ( = 0); superdeformed prolate hemispheroid ( = 0.63), and hyperdeformed prolate hemispheroid ( = 0.97) for i = - 0.76, -0.58, 0, 1, and 2, respectively, almost independent of the number of atoms in the cluster.
36.40.Qv - Stability and fragmentation of clusters.
71.45.-d - Collective effects.
61.46.Bc - Structure of clusters (e.g., metcars; not fragments of crystals; free or loosely aggregated or loosely attached to a substrate).
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