21,913 research outputs found
Thin Films of 3He -- Implications on the Identification of 3 He -A
Recently the identification of 3He-A with the axial state has been
questioned. It is suggested that the A-phase can actually be in the axiplanar
state. We point out in the present paper that experiments in a film geometry
may be useful to distinguish the above two possibilities. In particular a
second order phase transition between an axial and an axiplanar state would
occur as a function of thickness or temperature.Comment: 3 pages, no figures latex- revtex aps accepted by J. of Low
Temperature Physic
Broken-Symmetry Unrestricted Hybrid Density Functional Calculations on Nickel Dimer and Nickel Hydride
In the present work we investigate the adequacy of broken-symmetry
unrestricted density functional theory (DFT) for constructing the potential
energy curve of nickel dimer and nickel hydride, as a model for larger bare and
hydrogenated nickel cluster calculations. We use three hybrid functionals: the
popular B3LYP, Becke's newest optimized functional Becke98, and the simple
FSLYP functional (50% Hartree-Fock and 50% Slater exchange and LYP
gradient-corrected correlation functional) with two basis sets: all-electron
(AE) Wachters+f basis set and Stuttgart RSC effective core potential (ECP) and
basis set.
We find that, overall, the best agreement with experiment, comparable to that
of the high-level CASPT2, is obtained with B3LYP/AE, closely followed by
Becke98/AE and Becke98/ECP. FSLYP/AE and B3LYP/ECP give slightly worse
agreement with experiment, and FSLYP/ECP is the only method among the ones we
studied that gives an unaceptably large error, underestimating the dissociation
energy of nickel dimer by 28%, and being in the largest disagreement with the
experiment and the other theoretical predictions.Comment: 17 pages, 7 tables, 7 figures; submitted to J. Chem. Phys.;
Revtex4/LaTeX2e. v2 (8/5/04): New (and better) ECP results, without charge
density fitting (which was found to give large errors). Subtracted the
relativistic corrections from all experimental value
Zero delay synchronization of chaos in coupled map lattices
We show that two coupled map lattices that are mutually coupled to one
another with a delay can display zero delay synchronization if they are driven
by a third coupled map lattice. We analytically estimate the parametric regimes
that lead to synchronization and show that the presence of mutual delays
enhances synchronization to some extent. The zero delay or isochronal
synchronization is reasonably robust against mismatches in the internal
parameters of the coupled map lattices and we analytically estimate the
synchronization error bounds.Comment: 9 pages, 9 figures ; To appear in Phys. Rev.
Nature of non-magnetic strongly-correlated state in delta-plutonium
Ab-initio relativistic dynamical mean-field theory is applied to resolve the
long-standing controversy between theory and experiment in the "simple"
face-centered cubic phase of plutonium called delta-Pu. In agreement with
experiment, neither static nor dynamical magnetic moments are predicted. In
addition, the quasiparticle density of states reproduces not only the peak
close to the Fermi level, which explains the large coefficient of electronic
specific heat, but also main 5f features observed in photoelectron
spectroscopy.Comment: 9 pages, 3 figure
Casorati Determinant Form of Dark Soliton Solutions of the Discrete Nonlinear Schr\"odinger Equation
It is shown that the -dark soliton solutions of the integrable discrete
nonlinear Schr\"odinger (IDNLS) equation are given in terms of the Casorati
determinant. The conditions for reduction, complex conjugacy and regularity for
the Casorati determinant solution are also given explicitly. The relationship
between the IDNLS and the relativistic Toda lattice is discussed.Comment: First version was uploaded in 23 Jun 2005. Published in Journal of
the Physical Society of Japan in May, 200
Minimal Stochastic Model for Fermi's Acceleration
We introduce a simple stochastic system able to generate anomalous diffusion
both for position and velocity. The model represents a viable description of
the Fermi's acceleration mechanism and it is amenable to analytical treatment
through a linear Boltzmann equation. The asymptotic probability distribution
functions (PDF) for velocity and position are explicitly derived. The diffusion
process is highly non-Gaussian and the time growth of moments is characterized
by only two exponents and . The diffusion process is anomalous
(non Gaussian) but with a defined scaling properties i.e. and similarly for velocity.Comment: RevTeX4, 4 pages, 2 eps-figures (minor revision
Spin correlations among the charge carriers in an ordered stripe phase
We have observed a diffuse component to the low-energy magnetic excitation
spectrum of stripe-ordered La5/3Sr1/3NiO4 probed by neutron inelastic
scattering. The diffuse scattering forms a square pattern with sides parallel
and perpendicular to the stripe directions. The signal is dispersive, with a
maximum energy of ~10 meV. Probed at 2 meV the scattering decreases in strength
with increasing temperature, and is barely visible at 100 K. We argue that the
signal originates from dynamic, quasi- one-dimensional, antiferromagnetic
correlations among the stripe electrons.Comment: 4 pages, 4 figures. To be published in Physical Review Letter
Resonant Cyclotron Radiation Transfer Model Fits to Spectra from Gamma-Ray Burst GRB870303
We demonstrate that models of resonant cyclotron radiation transfer in a
strong field (i.e. cyclotron scattering) can account for spectral lines seen at
two epochs, denoted S1 and S2, in the Ginga data for GRB870303. Using a
generalized version of the Monte Carlo code of Wang et al. (1988,1989b), we
model line formation by injecting continuum photons into a static
plane-parallel slab of electrons threaded by a strong neutron star magnetic
field (~ 10^12 G) which may be oriented at an arbitrary angle relative to the
slab normal. We examine two source geometries, which we denote "1-0" and "1-1,"
with the numbers representing the relative electron column densities above and
below the continuum photon source plane. We compare azimuthally symmetric
models, i.e. models in which the magnetic field is parallel to the slab normal,
with models having more general magnetic field orientations. If the bursting
source has a simple dipole field, these two model classes represent line
formation at the magnetic pole, or elsewhere on the stellar surface. We find
that the data of S1 and S2, considered individually, are consistent with both
geometries, and with all magnetic field orientations, with the exception that
the S1 data clearly favor line formation away from a polar cap in the 1-1
geometry, with the best-fit model placing the line-forming region at the
magnetic equator. Within both geometries, fits to the combined (S1+S2) data
marginally favor models which feature equatorial line formation, and in which
the observer's orientation with respect to the slab changes between the two
epochs. We interpret this change as being due to neutron star rotation, and we
place limits on the rotation period.Comment: LaTeX2e (aastex.cls included); 45 pages text, 17 figures (on 21
pages); accepted by ApJ (to be published 1 Nov 1999, v. 525
VETA-I x ray test analysis
This interim report presents some definitive results from our analysis of the VETA-I x-ray testing data. It also provides a description of the hardware and software used in the conduct of the VETA-I x-ray test program performed at the MSFC x-ray Calibration Facility (XRCF). These test results also serve to supply data and information to include in the TRW final report required by DPD 692, DR XC04. To provide an authoritative compendium of results, we have taken nine papers as published in the SPIE Symposium, 'Grazing Incidence X-ray/EUV Optics for Astronomy and Projection Lithography' and have reproduced them as the content of this report
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