52 research outputs found
Surface term for the capillary condensation transitions in a slit geometry
It is shown that a bare simple fluid model (SFM) proposed some years ago for
studying adsorption between two semi-infinite solid walls can be improved by
modifying the surface term in the grand potential for the film phase. Such a
correction substantially improves the agreement between the predictions for
phase transitions provided by that SFM and results obtained from calculations
carried out for He with the density-functional method at zero temperature.
The corrective term depends on the strength of the adsorption potential and
observables of bulk helium.Comment: 4 pages, 1 table and 5 figure
Curvature effects on the surface thickness and tension at the free interface of He systems
The thickness and the surface energy at the free interface of
superfluid He are studied. Results of calculations carried out by using
density functionals for cylindrical and spherical systems are presented in a
unified way, including a comparison with the behavior of planar slabs. It is
found that for large species is independent of the geometry. The obtained
values of are compared with prior theoretical results and experimental
data. Experimental data favor results evaluated by adopting finite range
approaches. The behavior of and exhibit overshoots
similar to that found previously for the central density, the trend of these
observables towards their asymptotic values is examined.Comment: 35 pages, TeX, 5 figures, definitive versio
Finite size effects in adsorption of helium mixtures by alkali substrates
We investigate the behavior of mixed 3He-4He droplets on alkali surfaces at
zero temperature, within the frame of Finite Range Density Functional theory.
The properties of one single 3He atom on 4He_N4 droplets on different alkali
surfaces are addressed, and the energetics and structure of 4He_N4+3He_N3
systems on Cs surfaces, for nanoscopic 4He drops, are analyzed through the
solutions of the mean field equations for varying number N3 of 3He atoms. We
discuss the size effects on the single particle spectrum of 3He atoms and on
the shapes of both helium distributions.Comment: 12 pages, and 12 figures (PNG format
From nonwetting to prewetting: the asymptotic behavior of 4He drops on alkali substrates
We investigate the spreading of 4He droplets on alkali surfaces at zero
temperature, within the frame of Finite Range Density Functional theory. The
equilibrium configurations of several 4He_N clusters and their asymptotic trend
with increasing particle number N, which can be traced to the wetting behavior
of the quantum fluid, are examined for nanoscopic droplets. We discuss the size
effects, inferring that the asymptotic properties of large droplets correspond
to those of the prewetting film
A Density Functional for Liquid 3He Based on the Aziz Potential
We propose a new class of density functionals for liquid 3He based on the Aziz helium-helium interaction screened at short distances by the microscopically calculated two-body distribution function g(r). Our aim is to reduce to a minumum the unavoidable phenomenological ingredients inherent to any density functional approach. Results for the homogeneous liquid and droplets are presented and discussed. © 2006 American Institute of Physics.Fil:Hernández, E.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Szybisz, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Second-class currents in 0⁻→0⁺ and unique nuclear β transitions
The induced pseudotensor contribution to 0⁻ → 0⁺ and uniqueβ transitions has been analyzed starting from two possible forms of the nonrelativistic Hamiltonian. The role of mesonic corrections and mesonic second-class currents has been discussedFacultad de Ciencias Exacta
Dynamics of liquid He-4 in confined geometries from Time-Dependent Density Functional calculations
We present numerical results obtained from Time-Dependent Density Functional
calculations of the dynamics of liquid He-4 in different environments
characterized by geometrical confinement. The time-dependent density profile
and velocity field of He-4 are obtained by means of direct numerical
integration of the non-linear Schrodinger equation associated with a
phenomenological energy functional which describes accurately both the static
and dynamic properties of bulk liquid He-4. Our implementation allows for a
general solution in 3-D (i.e. no symmetries are assumed in order to simplify
the calculations). We apply our method to study the real-time dynamics of pure
and alkali-doped clusters, of a monolayer film on a weakly attractive surface
and a nano-droplet spreading on a solid surface.Comment: q 1 tex file + 9 Ps figure
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