3 research outputs found
Using mean field theory to determine the structure of uniform fluids
The structure of a uniform simple liquid is related to that of a reference
fluid with purely repulsive intermolecular forces in a self-consistently
determined external reference field (ERF) phi_ R. The ERF can be separated into
a harshly repulsive part phi_ R0 generated by the repulsive core of a reference
particle fixed at the origin and a more slowly varying part phi_ R1 arising
from a mean field treatment of the attractive forces. We use a generalized
linear response method to calculate the reference fluid structure, first
determining the response to the smoother part phi_ R1 of the ERF alone,
followed by the response to the harshly repulsive part. Both steps can be
carried out very accurately, as confirmed by MD simulations, and good agreement
with the structure of the full LJ fluid is found.Comment: 11 pages, 7 figure
Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids
We have carried out extensive equilibrium molecular dynamics (MD) simulations
to investigate the Liquid-Vapor coexistence in partially miscible binary and
ternary mixtures of Lennard-Jones (LJ) fluids. We have studied in detail the
time evolution of the density profiles and the interfacial properties in a
temperature region of the phase diagram where the condensed phase is demixed.
The composition of the mixtures are fixed, 50% for the binary mixture and
33.33% for the ternary mixture. The results of the simulations clearly indicate
that in the range of temperatures K, --in the scale of
argon-- the system evolves towards a metastable alternated liquid-liquid
lamellar state in coexistence with its vapor phase. These states can be
achieved if the initial configuration is fully disordered, that is, when the
particles of the fluids are randomly placed on the sites of an FCC crystal or
the system is completely mixed. As temperature decreases these states become
very well defined and more stables in time. We find that below K,
the alternated liquid-liquid lamellar state remains alive for 80 ns, in the
scale of argon, the longest simulation we have carried out. Nonetheless, we
believe that in this temperature region these states will be alive for even
much longer times.Comment: 18 Latex-RevTex pages including 12 encapsulated postscript figures.
Figures with better resolution available upon request. Accepted for
publication in Phys. Rev. E Dec. 1st issu