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

Abstract—A 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* = kBTframe0R/e2, where kB is the Boltzmann constant, T is the temperature, frame1 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 = 1–100 charges. At small N ~ 10, Thomson’s 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


Pleiades Publishing home page | journal home page | top

If you have any problems with this server, contact webmaster.