1,831 research outputs found
Dual characterization of critical fluctuations: Density functional theory & nonlinear dynamics close to a tangent bifurcation
We improve on the description of the relationship that exists between
critical clusters in thermal systems and intermittency near the onset of chaos
in low-dimensional systems. We make use of the statistical-mechanical language
of inhomogeneous systems and of the renormalization group (RG) method in
nonlinear dynamics to provide a more accurate, formal, approach to the subject.
The description of this remarkable correspondence encompasses, on the one hand,
the density functional formalism, where classical and quantum mechanical
analogues match the procedure for one-dimensional clusters, and, on the other,
the RG fixed-point map of functional compositions that captures the essential
dynamical behavior. We provide details of how the above-referred theoretical
approaches interrelate and discuss the implications of the correspondence
between the high-dimensional (degrees of freedom) phenomenon and
low-dimensional dynamics.Comment: 8 figure
Cluster radioactivity of Th isotopes in the mean-field HFB theory
Cluster radioactivity is described as a very mass asymmetric fission process.
The reflection symmetry breaking octupole moment has been used in a mean field
HFB theory as leading coordinate instead of the quadrupole moment usually used
in standard fission calculations. The procedure has been applied to the study
of the ``very mass asymmetric fission barrier'' of several even-even Thorium
isotopes. The masses of the emitted clusters as well as the corresponding
half-lives have been evaluated on those cases where experimental data exist.Comment: Contribution to XIV Nuclear Physics Workshop at Kazimierz Dolny,
Poland, Sept. 26-29, 200
Typical length scales in conducting disorderless networks
We take advantage of a recently established equivalence, between the
intermittent dynamics of a deterministic nonlinear map and the scattering
matrix properties of a disorderless double Cayley tree lattice of connectivity
, to obtain general electronic transport expressions and expand our
knowledge of the scattering properties at the mobility edge. From this we
provide a physical interpretation of the generalized localization length.Comment: 12 pages, 3 figure
A variational approach to approximate particle number projection with effective forces
Kamlah's second order method for approximate particle number projection is
applied for the first time to variational calculations with effective forces.
High spin states of normal and superdeformed nuclei have been calculated with
the finite range density dependent Gogny force for several nuclei. Advantages
and drawbacks of the Kamlah second order method as compared to the
Lipkin-Nogami recipe are thoroughly discussed. We find that the Lipkin-Nogami
prescription occasionally may fail to find the right energy minimum in the
strong pairing regime and that Kamlah's second order approach, though providing
better results than the LN one, may break down in some limiting situations.Comment: 16 pages, 8 figure
Electromagnetic transition strengths in soft deformed nuclei
Spectroscopic observables such as electromagnetic transitions strengths can
be related to the properties of the intrinsic mean-field wave function when the
latter are strongly deformed, but the standard rotational formulas break down
when the deformation decreases. Nevertheless there is a well-defined, non-zero,
spherical limit that can be evaluated in terms of overlaps of mean-field
intrinsic deformed wave functions. We examine the transition between the
spherical limit and strongly deformed one for a range of nuclei comparing the
two limiting formulas with exact projection results. We find a simple criterion
for the validity of the rotational formula depending on ,
the mean square fluctuation in the angular momentum of the intrinsic state. We
also propose an interpolation formula which describes the transition strengths
over the entire range of deformations, reducing to the two simple expressions
in the appropriate limits.Comment: 16 pages, 5 figures, supplemental material include
Parallels between the dynamics at the noise-perturbed onset of chaos in logistic maps and the dynamics of glass formation
We develop the characterization of the dynamics at the noise-perturbed edge
of chaos in logistic maps in terms of the quantities normally used to describe
glassy properties in structural glass formers. Following the recognition [Phys.
Lett. \textbf{A 328}, 467 (2004)] that the dynamics at this critical attractor
exhibits analogies with that observed in thermal systems close to
vitrification, we determine the modifications that take place with decreasing
noise amplitude in ensemble and time averaged correlations and in diffusivity.
We corroborate explicitly the occurrence of two-step relaxation, aging with its
characteristic scaling property, and subdiffusion and arrest for this system.
We also discuss features that appear to be specific of the map.Comment: Revised version with substantial improvements. Revtex, 8 pages, 11
figure
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