11,506 research outputs found
Algebraic Approach to Molecular thermodynamics
An algebraic model based on Lie-algebraic and discrete symmetry techniques is
applied to the analysis of thermodynamic vibrational properties of molecules.
The local anharmonic effects are described by a Morse-like potential and the
corresponding anharmonic bosons are associated with the SU(2) algebra. A
vibrational high-temperature partition function and the related thermodynamic
functions are derived and studied in terms of the parameters of the model. The
idea of a critical temperature is introduced in relation with the specific
heat. A physical interpretation of a quantum deformation associated with the
model is given.Comment: 18 pages, 6 figures, submitted to J Physics: Condensed Matte
Positive solutions for asymptotically linear problems in exterior domains
The existence of a positive solution for a class of asymptotically lin- ear
problems in exterior domains is established via a linking argument on the
Nehari manifold and by means of a barycenter function
Roughness correction to the Casimir force : Beyond the Proximity Force Approximation
We calculate the roughness correction to the Casimir effect in the parallel
plates geometry for metallic plates described by the plasma model. The
calculation is perturbative in the roughness amplitude with arbitrary values
for the plasma wavelength, the plate separation and the roughness correlation
length. The correction is found to be always larger than the result obtained in
the Proximity Force Approximation.Comment: 7 pages, 3 figures, v2 with minor change
Particle Creation by a Moving Boundary with Robin Boundary Condition
We consider a massless scalar field in 1+1 dimensions satisfying a Robin
boundary condition (BC) at a non-relativistic moving boundary. We derive a
Bogoliubov transformation between input and output bosonic field operators,
which allows us to calculate the spectral distribution of created particles.
The cases of Dirichlet and Neumann BC may be obtained from our result as
limiting cases. These two limits yield the same spectrum, which turns out to be
an upper bound for the spectra derived for Robin BC. We show that the particle
emission effect can be considerably reduced (with respect to the
Dirichlet/Neumann case) by selecting a particular value for the oscillation
frequency of the boundary position
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