282 research outputs found
Electron correlation energy in confined two-electron systems
Radial, angular and total correlation energies are calculated for four
two-electron systems with atomic numbers Z=0-3 confined within an impenetrable
sphere of radius R. We report accurate results for the non-relativistic,
restricted Hartree-Fock and radial limit energies over a range of confinement
radii from 0.05 - 10 a0. At small R, the correlation energies approach limiting
values that are independent of Z while at intermediate R, systems with Z > 1
exhibit a characteristic maximum in the correlation energy resulting from an
increase in the angular correlation energy which is offset by a decrease in the
radial correlation energy
Net Fisher information measure versus ionization potential and dipole polarizability in atoms
The net Fisher information measure, defined as the product of position and
momentum Fisher information measures and derived from the non-relativistic
Hartree-Fock wave functions for atoms with Z=1-102, is found to correlate well
with the inverse of the experimental ionization potential. Strong direct
correlations of the net Fisher information are also reported for the static
dipole polarizability of atoms with Z=1-88. The complexity measure, defined as
the ratio of the net Onicescu information measure and net Fisher information,
exhibits clearly marked regions corresponding to the periodicity of the atomic
shell structure. The reported correlations highlight the need for using the net
information measures in addition to either the position or momentum space
analogues. With reference to the correlation of the experimental properties
considered here, the net Fisher information measure is found to be superior
than the net Shannon information entropy.Comment: 16 pages, 6 figure
Effect of Processing on Morphology of Hydroxyapatites: Bioactive Glasses and Crystalline Composites
Recent studies on multinary oxides for applications as laser hosts and high dielectric capacitors have shown that processing at high temperature provides glassy or crystalline materials based on thermal treatments and cooling rates. Since hydroxyapatites are now subject of great interests due to their bioactivity, interest in producing soft and hard materials with glassy and crystalline nature by processing parameters has become very important. Crystalline materials by using Bridgman, Czochralski and flux growth methods are costly and require huge investment. We have observed that even low temperature solidification in organic flux produced oriented fibers. This organic treated material has different characteristics than in situ oxide materials prepared by sintering and grain growth. Examples of phosphate and silicate-based systems will be presented to demonstrate soft and hard materials. Effect of TiO2 and other hardening elements will be also reported
Cosmic F- and D-strings
Macroscopic fundamental and Dirichlet strings have several potential
instabilities: breakage, tachyon decays, and confinement by axion domain walls.
We investigate the conditions under which metastable strings can exist, and we
find that such strings are present in many models. There are various
possibilities, the most notable being a network of (p,q) strings. Cosmic
strings give a potentially large window into string physics.Comment: 27 pages, 5 figures; v. 5: JHEP style, added comments in section 2.
Deviation From \Lambda CDM With Cosmic Strings Networks
In this work, we consider a network of cosmic strings to explain possible
deviation from \Lambda CDM behaviour. We use different observational data to
constrain the model and show that a small but non zero contribution from the
string network is allowed by the observational data which can result in a
reasonable departure from \Lambda CDM evolution. But by calculating the
Bayesian Evidence, we show that the present data still strongly favour the
concordance \Lambda CDM model irrespective of the choice of the prior.Comment: 15 Pages, Latex Style, 4 eps figures, Revised Version, Accepted for
publication in European Physical Journal
Response function analysis of excited-state kinetic energy functional constructed by splitting k-space
Over the past decade, fundamentals of time independent density functional
theory for excited state have been established. However, construction of the
corresponding energy functionals for excited states remains a challenging
problem. We have developed a method for constructing functionals for excited
states by splitting k-space according to the occupation of orbitals. In this
paper we first show the accuracy of kinetic energy functional thus obtained. We
then perform a response function analysis of the kinetic energy functional
proposed by us and show why method of splitting the k-space could be the method
of choice for construction of energy functionals for excited states.Comment: 11 page
Scaling properties of composite information measures and shape complexity for hydrogenic atoms in parallel magnetic and electric fields
The scaling properties of various composite information-theoretic measures
(Shannon and R\'enyi entropy sums, Fisher and Onicescu information products,
Tsallis entropy ratio, Fisher-Shannon product and shape complexity) are studied
in position and momentum spaces for the non-relativistic hydrogenic atoms in
the presence of parallel magnetic and electric fields. Such measures are found
to be invariant at the fixed values of the scaling parameters given by and . Numerical results which support the validity of the scaling
properties are shown by choosing the representative example of the position
space shape complexity. Physical significance of the resulting scaling
behaviour is discussed.Comment: 10 pages, 2 figure
Statefinder Parameter for Varying G in Three Fluid System
In this work, we have considered variable G in flat FRW universe filled with
the mixture of dark energy, dark matter and radiation. If there is no
interaction between the three fluids, the deceleration parameter and
statefinder parameters have been calculated in terms of dimensionless density
parameters which can be fixed by observational data. Also the interaction
between three fluids has been analyzed due to constant . The statefinder
parameters also calculated in two cases: pressure is constant and pressure is
variable.Comment: 5 pages, Accepted for publication in "Astrophysics and Space Science
Quasinormal modes for tensor and vector type perturbation of Gauss Bonnet black holes using third order WKB approach
We obtain the quasinormal modes for tensor perturbations of Gauss-Bonnet (GB)
black holes in dimensions and vector perturbations in
and 8 dimensions using third order WKB formalism. The tensor perturbation for
black holes in is not considered because of the fact that it is unstable
to tensor mode perturbations. In the case of uncharged GB black hole, for both
tensor and vector perturbations, the real part of the QN frequency increases as
the Gauss-Bonnet coupling () increases. The imaginary part first
decreases upto a certain value of and then increases with
for both tensor and vector perturbations. For larger values of , the
QN frequencies for vector perturbation differs slightly from the QN frequencies
for tensorial one. It has also been shown that as , the
quasinormal mode frequency for tensor and vector perturbation of the
Schwarzschild black hole can be obtained. We have also calculated the
quasinormal spectrum of the charged GB black hole for tensor perturbations.
Here we have found that the real oscillation frequency increases, while the
imaginary part of the frequency falls with the increase of the charge. We also
show that the quasinormal frequencies for scalar field perturbations and the
tensor gravitational perturbations do not match as was claimed in the
literature. The difference in the result increases if we increase the GB
coupling.Comment: 17 pages, 11 figures, change in title and abstract, new equations and
results added for QN frequencies for vector perturbations, new referencees
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Possible dark energy imprints in gravitational wave spectrum of mixed neutron-dark-energy stars
In the present paper we study the oscillation spectrum of neutron stars
containing both ordinary matter and dark energy in different proportions.
Within the model we consider, the equilibrium configurations are numerically
constructed and the results show that the properties of the mixed
neuron-dark-energy star can differ significantly when the amount of dark energy
in the stars is varied. The oscillations of the mixed neuron-dark-energy stars
are studied in the Cowling approximation. As a result we find that the
frequencies of the fundamental mode and the higher overtones are strongly
affected by the dark energy content. This can be used in the future to detect
the presence of dark energy in the neutron stars and to constrain the
dark-energy models.Comment: 17 pages, 8 figures, LaTe
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