Darmstadt 2008 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P I: Poster: Staubige Plasmen, Dichte Plasmen

P I.1: Poster

Dienstag, 11. März 2008, 08:30–10:30, Poster C3

Probability of Metastable States in Yukawa Clusters — •Hanno Kählert, Patrick Ludwig, and Michael Bonitz — CAU zu Kiel, ITAP, Leibnizstraße 15, D-24098 Kiel

The ground states of spherical, trapped Yukawa clusters are well known from molecular dynamics (MD) and Monte Carlo simulations [1,2]. In this contribution we focus on metastable states which are frequently observed under typical experimental conditions of spherical dust crystals [3]. Using MD the annealing process is simulated to investigate the probabilities of finding metastable states in a system of N=27 and N=31 particles. It is shown that slow cooling favours the ground state over metastable states. Further we show that the screening length strongly affects the results compared to Coulomb interaction.

As a second approach an analytical theory based on the classical canonical partition function with an harmonic approximation [4] is performed and allows to gain insight into the mechanism being responsible for the occurrence probabilities in thermodynamic equilibrium. The results show that only a small interval of parameters is capable of explaining the experimental findings.

[1] P. Ludwig, S. Kosse, M. Bonitz, Phys. Rev. E 71, 46403 (2005)

[2] H. Baumgartner et al., submitted for publication

[3] D. Block et al., Experiments on metastable states of three-dimensional trapped particle clusters, submitted to Phys. Rev. Letters

[4] F. Baletto and R. Ferrando, Rev. Mod. Phys. 77, No. 1, (2005)