Crystallization and Melting of a System of Charges
in a Liquid Helium Cluster
A. M. Livshits and Yu. E. Lozovik
Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow oblast, 142092 Russia
e-mail: livshits@isan.troitsk.ru
Received January 26, 2007
AbstractA system of like (positive or negative) charges forming snowballs or bubbles in a three-dimen-
sional liquid helium cluster is investigated. The charges are confined inside the cluster by an image potential
produced by the polarization of liquid helium. The stability of a multiply charged helium cluster is considered.
Computer simulations are used to investigate the crystallization and melting of the system of charges depending
on the dimensionless parameter T* = kBT
R/e2, where kB is the Boltzmann constant, T is the temperature,
is
the dielectric constant of liquid helium, R is the cluster radius, and e is a unit charge. Various characteristics,
including symmetry groups and moments, have been found for equilibrium configurations of charges in a clus-
ter with N = 1100 charges. At small N ~ 10, Thomsons model of successive filling of belts of charges can
be used to describe the structure of equilibrium configurations of charges. At large N, the description of the
structure formed by charges using the idea of a quasi-two-dimensional closed triangular lattice with topolog-
ical defects is more adequate. Formally, this description is valid starting from N = 4. The melting of a lattice
of charges is described. A number of our conclusions can be generalized to clusters of other noble gases.
PACS numbers: 61.46.Bc, 36.40.Wa, 67.40.Jg, 64.70.Nd
DOI: 10.1134/S1063776107090142
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