15,467 research outputs found
Dynamical System of Scalar Field from 2-Dimension to 3-D and its Cosmological Implication
We give the three-dimensional dynamical autonomous systems for most of the
popular scalar field dark energy models including (phantom) quintessence,
(phantom) tachyon, k-essence and general non-canonical scalar field models,
change the dynamical variables from variables to observable
related variables , and show the intimate
relationships between those scalar fields that the three-dimensional system of
k-essence can reduce to (phantom) tachyon, general non-canonical scalar field
can reduce to (phantom) quintessence and k-essence can also reduce to (phantom)
quintessence for some special cases. For the applications of the
three-dimensional dynamical systems, we investigate several special cases and
give the exactly dynamical solutions in detail. In the end of this paper, we
argue that, it is more convenient and also has more physical meaning to express
the differential equations of dynamical systems in instead of variables and to investigate the
dynamical system in 3-Dimension instead of 2-Dimension. We also raise a
question about the possibility of the chaotic behavior in the spatially flat
single scalar field FRW cosmological models in the presence of ordinary matter.Comment: 20 pages, 8 figures,some references added. Minor changes according to
the suggestions from referee
Maxwell-Hydrodynamic Model for Simulating Nonlinear Terahertz Generation from Plasmonic Metasurfaces
The interaction between the electromagnetic field and plasmonic
nanostructures leads to both the strong linear response and inherent nonlinear
behavior. In this paper, a time-domain hydrodynamic model for describing the
motion of electrons in plasmonic nanostructures is presented, in which both
surface and bulk contributions of nonlinearity are considered. A coupled
Maxwell-hydrodynamic system capturing full-wave physics and free electron
dynamics is numerically solved with the parallel finite-difference time-domain
(FDTD) method. The validation of the proposed method is presented to simulate
linear and nonlinear responses from a plasmonic metasurface. The linear
response is compared with the Drude dispersion model and the nonlinear
terahertz emission from a difference-frequency generation process is validated
with theoretical analyses. The proposed scheme is fundamentally important to
design nonlinear plasmonic nanodevices, especially for efficient and broadband
THz emitters.Comment: 8 pages, 7 figures, IEEE Journal on Multiscale and Multiphysics
Computational Techniques, 201
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