8,480 research outputs found
Exchange and correlation energies of ground states of atoms and molecules in strong magnetic fields
Using a Hartree-Fock mesh method and a configuration interaction approach
based on a generalized Gaussian basis set we investigate the behaviour of the
exchange and correlation energies of small atoms and molecules, namely th e
helium and lithium atom as well as the hydrogen molecule, in the presence of a
magnetic field covering the regime B=0-100a.u. In general the importance of the
exchange energy to the binding properties of at oms or molecules increases
strongly with increasing field strength. This is due to the spin-flip
transitions and in particular due to the contributions of the tightly bound
hydrogenic state s which are involved in the corresponding ground states of
different symmetries. In contrast to the exchange energy the correlation energy
becomes less relevant with increasing field strength. This holds for the
individual configurations constituting the ground state and for the crossovers
of the global ground state.Comment: 4 Figures acc.f.publ.in Phys.Rev.
Decay Rate and Hyperfine Structure of the bound mu+ mu- system
Results are obtained for the decay rate of ortho and para states and for the
hyperfine structure of the dimuonic system mu+ mu- (dimuonium). We calculate
next--to-leading order radiative corrections. It is shown that previously
reported results for the decay rate of ortho states are incomplete. The decay
rate is strongly influenced by the electronic vacuum polarization in the far
time-like asymptotic region and thus allows for a test of QED in a previously
unexplored kinematic regime.Comment: 6 pages, LaTeX, 4 figures, some alterations from Phys Lett B versio
On UHECR energy estimation algorithms based on the measurement of electromagnetic component parameters in EAS
Model calculations are performed of extensive air shower (EAS) component
energies using a variety of hadronic interaction parameters. A conversion
factor from electromagnetic component energy to the energy of ultra-high energy
cosmic rays (UHECRs) and its model and primary mass dependence is studied. It
is shown that model dependence of the factor minimizes under the necessary
condition of the same maximum position and muon content of simulated showers.Comment: contracted version is accepted for publication in Doklady Physic
Pure-radiation gravitational fields with a simple twist and a Killing vector
Pure-radiation solutions are found, exploiting the analogy with the Euler-
Darboux equation for aligned colliding plane waves and the Euler-Tricomi
equation in hydrodynamics of two-dimensional flow. They do not depend on one of
the spacelike coordinates and comprise the Hauser solution as a special
subcase.Comment: revtex, 9 page
Crossroads
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel
The Nutation Effect And Sit On The Exciton Levels
The theory of the nutation effect and SIT on the exciton levels, where the polariton dispersion is taken into account, are considered. © 1976, Taylor & Francis Group, LLC. All rights reserved
On the nature of Coulomb corrections to the e^+e^- pair production in ultrarelativistic heavy-ion collisions
We manifest the origin of the wrong conclusion made by several groups of
authors on the absence of Coulomb corrections to the cross section of the
e^+e^- pair production in ultrarelativistic heavy-ion collisions. The source of
the mistake is connected with an incorrect passage to the limit in the
expression for the cross section. When this error is eliminated, the Coulomb
corrections do not vanish and agree with the results obtained within the
Weizs\"acker-Williams approximation.Comment: 7 pages, LaTe
Evolution of Baryon-Free Matter Produced in Relativistic Heavy-Ion Collisions
A 3-fluid hydrodynamic model is introduced for simulating heavy-ion
collisions at incident energies between few and about 200 AGeV. In addition to
the two baryon-rich fluids of 2-fluid models, the new model incorporates a
third, baryon-free (i.e. with zero net baryonic charge) fluid which is created
in the mid-rapidity region. Its evolution is delayed due to a formation time
, during which the baryon-free fluid neither thermalizes nor interacts
with the baryon-rich fluids. After formation it thermalizes and starts to
interact with the baryon-rich fluids. It is found that for =0 the
interaction strongly affects the baryon-free fluid. However, at reasonable
finite formation time, =1 fm/c, the effect of this interaction turns out
to be substantially reduced although still noticeable. Baryonic observables are
only slightly affected by the interaction with the baryon-free fluid.Comment: 17 pages, 3 figures, submitted to the issue of Phys. of Atomic Nuclei
dedicated to S.T. Belyaev on the occasion of his 80th birthday, typos
correcte
Ion channeling in CuInSe2 single crystals
CuInSe2 single crystals are studied by the Rutherford Backscattering of 2 MeV helium ions involving axial channeling along the 〈2 2 1〉 direction of the chalcopyrite lattice. Experimental values of the critical angle and normalized minimum yield are measured and compared with theory. The concentration of point defects separately in the Cu, In, and Se sublattices, determined from the comparison of experimental and theoretical minimum yields, are estimated as 4.7 × 1020, 1.0 × 1020, and 5.7 × 1020 cm-3, respectively. © 2013 Elsevier B.V. All rights reserved
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