DOI: 10.1209/epl/i2006-10190-9
Monte Carlo study of the evaporation/condensation transition of Ising droplets
A. Nußbaumer1, E. Bittner1, T. Neuhaus2 and W. Janke11 Institut für Theoretische Physik and Centre for Theoretical Sciences (NTZ) Universität Leipzig - Augustusplatz 10/11, D-04109 Leipzig, Germany
2 John von Neumann-Institut für Computing, Forschungszentrum Jülich D-52425 Jülich, Germany
received 7 May 2006; accepted in final form 18 July 2006
published online 10 August 2006
Abstract
In recent analytical work, Biskup et al. (Europhys. Lett.,
60 (2002) 21) studied the behaviour of d-dimensional
finite-volume liquid-vapour systems at a fixed excess
of
particles above the ambient gas density. By identifying a
dimensionless parameter
and a universal constant
, they showed in the limit of large system sizes
that for
the
excess is absorbed in the background ("evaporated" system), while
for
a droplet of the dense phase occurs
("condensed" system). Also the fraction
of excess
particles forming the droplet is given explicitly. Furthermore,
they argue that the same is true for solid-gas systems.
By making use of the well-known equivalence of the lattice-gas
picture with the spin-(1/2) Ising model, we performed Monte Carlo
simulations of the Ising model with nearest-neighbour couplings on a
square lattice with periodic boundary conditions at fixed
magnetisation, corresponding to a fixed particles excess. To test
the applicability of
the analytical results to much smaller, practically accessible
system sizes, we
measured the largest minority droplet,
corresponding to the solid phase, at various system sizes (
). Using analytic values for the spontaneous
magnetisation m0, the susceptibility
and the Wulff
interfacial free energy density
for the infinite system,
we were able to determine
numerically in very good
agreement with the theoretical prediction.
05.70.Fh - Phase transitions: general studies.
02.70.Uu - Applications of Monte Carlo methods.
75.10.Hk - Classical spin models.
© EDP Sciences 2006


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