27,273 research outputs found
On the use of the approximation in atomic calculations
We demonstrate that approximation is a good starting point for the
configuration interaction calculations for many-electron atoms and ions. is
the total number of electrons in the neutral atom, is the number of valence
electrons. is the self-consistent Hartree Fock potential for a
closed-shell ion with all valence electrons removed. Using of the
approximation considerably simplifies the many-body perturbation theory for the
core-valence correlations. It makes it easier to include higher-order
correlations which often significantly improves the accuracy of the
calculations. Calculations for krypton and barium and their positive ions are
presented for illustration.Comment: 5 pages,1 figure, submitted to Phys. Rev.
Measurement of HO2 and other trace gases in the stratosphere using a high resolution far-infrared spectrometer at 28 KM
The major events and results to date of the ongoing program of measuring stratospheric composition by the technique of far-infrared Fourier-transform spectroscopy from a balloon-borne platform are reviewed. The highlights of this period were the two balloon flight campaigns which were performed at Palestine, Texas, both of which produced large amounts of scientifically useful data
Band gaps in pseudopotential self-consistent GW calculations
For materials which are incorrectly predicted by density functional theory to
be metallic, an iterative procedure must be adopted in order to perform GW
calculations. In this paper we test two iterative schemes based on the
quasi-particle and pseudopotential approximations for a number of inorganic
semiconductors whose electronic structures are well known from experiment.
Iterating just the quasi-particle energies yields a systematic, but modest
overestimate of the band gaps, confirming conclusions drawn earlier for CaB_6
and YH_3. Iterating the quasi-particle wave functions as well gives rise to an
imbalance between the Hartree and Fock potentials and results in bandgaps in
far poorer agreement with experiment.Comment: 5 pages, 2 figures, 2 table
The Durham Statement Two Years Later: Open Access in the Law School Journal Environment
The Durham Statement on Open Access to Legal Scholarship, drafted by a group of academic law library directors, was promulgated in February 2009. It calls for two things: (1) open access publication of law school–published journals; and (2) an end to print publication of law journals, coupled with a commitment to keeping the electronic versions available in “stable, open, digital formats.” The two years since the Statement was issued have seen increased publication of law journals in openly available electronic formats, but little movement toward all-electronic publication. This article discusses the issues raised by the Durham Statement, the current state of law journal publishing, and directions forward
Test of Fermi Gas Model and Plane-Wave Impulse Approximation Against Electron-Nucleus Scattering Data
A widely used relativistic Fermi gas model and plane-wave impulse
approximation are tested against electron-nucleus scattering data. Inclusive
quasi-elastic cross section are calculated and compared with high-precision
data for C, O, and Ca. A dependence of agreement between calculated cross
section and data on a momentum transfer is shown. Results for the C(nu_mu,mu)
reaction are presented and compared with experimental data of the LSND
collaboration.Comment: 10 pages, 8 figure
Quasi-elastic neutrino charged-current scattering cross sections on oxygen
The charged-current quasi-elastic scattering of muon neutrinos on oxygen
target is computed for neutrino energies between 200 MeV and 2.5 GeV using the
relativistic distorted-wave impulse approximation with relativistic optical
potential, which was earlier successfully applied to describe electron-nucleus
data. We study both neutrino and electron processes and show that the reduced
exclusive cross sections for neutrino and electron scattering are similar. The
comparison with the relativistic Fermi gas model (RFGM), which is widely used
in data analyses of neutrino experiments, shows that the RFGM fails completely
when applied to exclusive cross section data and leads to overestimated values
of inclusive and total cross sections. We also found significant nuclear-model
dependence of exclusive, inclusive and total cross sections for about 1 GeV
energy.Comment: 30 pages, 11 figures; final version to appear in Phys. Rev.
Neutrons transition densities for the multiplet of states in Zr
The neutron transition densities of the levels in Zr were
extracted in the process of analysing ({\bf p},p') scattering at 400 Mev. Its
comparison with the proton transition densities for these levels was
undertaken. The radial shapes of the experimental neutron and proton transition
densities for each state were found to be different.Comment: 9 pages, 4 figure
On the shot-noise limit of a thermal current
The noise power spectral density of a thermal current between two macroscopic
dielectric bodies held at different temperatures and connected only at a
quantum point contact is calculated. Assuming the thermal energy is carried
only by phonons, we model the quantum point contact as a mechanical link,
having a harmonic spring potential. In the weak coupling, or weak-link limit,
we find the thermal current analog of the well-known electronic shot-noise
expression.Comment: 4 pages, 1 figur
HIV infection and domestic smoke exposure, but not human papillomavirus, are risk factors for esophageal squamous cell carcinoma in Zambia: a case-control study
(c) 2015 The Authors. Cancer Medicine published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
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