177 research outputs found
SCOZA for Monolayer Films
We show the way in which the self-consistent Ornstein-Zernike approach
(SCOZA) to obtaining structure factors and thermodynamics for Hamiltonian
models can best be applied to two-dimensional systems such as thin films. We
use the nearest-neighbor lattice gas on a square lattice as an illustrative
example.Comment: 10 pages, 5 figure
The Casimir Problem of Spherical Dielectrics: Quantum Statistical and Field Theoretical Approaches
The Casimir free energy for a system of two dielectric concentric nonmagnetic
spherical bodies is calculated with use of a quantum statistical mechanical
method, at arbitrary temperature. By means of this rather novel method, which
turns out to be quite powerful (we have shown this to be true in other
situations also), we consider first an explicit evaluation of the free energy
for the static case, corresponding to zero Matsubara frequency ().
Thereafter, the time-dependent case is examined. For comparison we consider the
calculation of the free energy with use of the more commonly known field
theoretical method, assuming for simplicity metallic boundary surfaces.Comment: 31 pages, LaTeX, one new reference; version to appear in Phys. Rev.
Casimir force between two ideal-conductor walls revisited
The high-temperature aspects of the Casimir force between two neutral
conducting walls are studied. The mathematical model of "inert" ideal-conductor
walls, considered in the original formulations of the Casimir effect, is based
on the universal properties of the electromagnetic radiation in the vacuum
between the conductors, with zero boundary conditions for the tangential
components of the electric field on the walls. This formulation seems to be in
agreement with experiments on metallic conductors at room temperature. At high
temperatures or large distances, at least, fluctuations of the electric field
are present in the bulk and at the surface of a particle system forming the
walls, even in the high-density limit: "living" ideal conductors. This makes
the enforcement of the inert boundary conditions inadequate. Within a hierarchy
of length scales, the high-temperature Casimir force is shown to be entirely
determined by the thermal fluctuations in the conducting walls, modelled
microscopically by classical Coulomb fluids in the Debye-H\"{u}ckel regime. The
semi-classical regime, in the framework of quantum electrodynamics, is studied
in the companion letter by P.R.Buenzli and Ph.A.Martin, cond-mat/0506363,
Europhys.Lett.72, 42 (2005).Comment: 7 pages.One reference updated. Domain of validity of eq.(11)
correcte
On the Temperature Dependence of the Casimir Effect
The temperature dependence of the Casimir force between a real metallic plate
and a metallic sphere is analyzed on the basis of optical data concerning the
dispersion relation of metals such as gold and copper. Realistic permittivities
imply, together with basic thermodynamic considerations, that the transverse
electric zero mode does not contribute. This results in observable differences
with the conventional prediction, which does not take this physical requirement
into account. The results are shown to be consistent with the third law of
thermodynamics, as well as being consistent with current experiments. However,
the predicted temperature dependence should be detectable in future
experiments. The inadequacies of approaches based on {\it ad hoc} assumptions,
such as the plasma dispersion relation and the use of surface impedance without
transverse momentum dependence, are discussed.Comment: 14 pages, 3 eps figures, revtex4. New version includes clarifications
and new reference. Accepted for publication in Phys. Rev.
Analytical and Numerical Demonstration of How the Drude Dispersive Model Satisfies Nernst's Theorem for the Casimir Entropy
In view of the current discussion on the subject, an effort is made to show
very accurately both analytically and numerically how the Drude dispersive
model, assuming the relaxation is nonzero at zero temperature (which is the
case when impurities are present), gives consistent results for the Casimir
free energy at low temperatures. Specifically, we find that the free energy
consists essentially of two terms, one leading term proportional to T^2, and a
next term proportional to T^{5/2}. Both these terms give rise to zero Casimir
entropy as T -> 0, thus in accordance with Nernst's theorem.Comment: 11 pages, 4 figures; minor changes in the discussion. Contribution to
the QFEXT07 proceedings; matches version to be published in J. Phys.
Analytical and Numerical Verification of the Nernst Theorem for Metals
In view of the current discussion on the subject, an effort is made to show
very accurately both analytically and numerically how the Drude dispersion
model gives consistent results for the Casimir free energy at low temperatures.
Specifically, for the free energy near T=0 we find the leading term to be
proportional to T^2 and the next-to-leading term proportional to T^{5/2}. These
terms give rise to zero Casimir entropy as T approaches zero, and is thus in
accordance with Nernst's theorem.Comment: 19 pages latex, 3 figures. v4: Figures updated. This is the final
version, accepted for publication in Physical Review
What is the Temperature Dependence of the Casimir Effect?
There has been recent criticism of our approach to the Casimir force between
real metallic surfaces at finite temperature, saying it is in conflict with the
third law of thermodynamics and in contradiction with experiment. We show that
these claims are unwarranted, and that our approach has strong theoretical
support, while the experimental situation is still unclear.Comment: 6 pages, REVTeX, final revision includes two new references and
related discussio
Reply to "Comment on 'Analytic and Numerical Verification of the Nernst Theorem for Metals'"
In this Reply to the preceding Comment of Klimchitskaya and Mostepanenko (cf.
also quant-ph/0703214), we summarize and maintain our position that the Drude
dispersion relation when inserted in the Lifshitz formula gives a
thermodynamically satisfactory description of the Casimir force, also in the
limiting case when the relaxation frequency goes to zero (perfect crystals).Comment: 4 pages, no figures; to appear in Phys. Rev.
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