556 research outputs found
Assessment of density functional approximations for the hemibonded structure of water dimer radical cation
Due to the severe self-interaction errors associated with some density
functional approximations, conventional density functionals often fail to
dissociate the hemibonded structure of water dimer radical cation (H2O)2+ into
the correct fragments: H2O and H2O+. Consequently, the binding energy of the
hemibonded structure (H2O)2+ is not well-defined. For a comprehensive
comparison of different functionals for this system, we propose three criteria:
(i) The binding energies, (ii) the relative energies between the conformers of
the water dimer radical cation, and (iii) the dissociation curves predicted by
different functionals. The long-range corrected (LC) double-hybrid functional,
omegaB97X-2(LP) [J.-D. Chai and M. Head-Gordon, J. Chem. Phys., 2009, 131,
174105.], is shown to perform reasonably well based on these three criteria.
Reasons that LC hybrid functionals generally work better than conventional
density functionals for hemibonded systems are also explained in this work.Comment: 10 pages, 5 figures, 4 table
Laminar flow and heat transfer characteristics of interrupted microchannel heat sink with ribs in the transverse microchambers
publisher: Elsevier articletitle: Laminar flow and heat transfer characteristics of interrupted microchannel heat sink with ribs in the transverse microchambers journaltitle: International Journal of Thermal Sciences articlelink: http://dx.doi.org/10.1016/j.ijthermalsci.2016.06.029 content_type: article copyright: © 2016 Elsevier Masson SAS. All rights reserved.The work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of the UK through research grant (EP/L001233/1) and the National Natural Science Foundation of China (51576005)
Study of the P-wave charmonium state \chi_{cJ} in \psi(2S) decays
The processes , and have been studied using a sample of produced
decays. We determine the total width of the to be
MeV. We present the first
measurement of the branching fraction , where the first error is statistical and the
second one systematic. Branching fractions of and
are also reported.Comment: 10 pages, revtex, 3 figures, 2 table
Observation of in
Using a sample of events recorded with
the BESIII detector at the symmetric electron positron collider BEPCII, we
report the observation of the decay of the charmonium state
into a pair of mesons in the process
. The branching fraction is measured for the first
time to be , where the first uncertainty is
statistical, the second systematic and the third is from the uncertainty of
. The mass and width of the are
determined as MeV/ and
MeV.Comment: 13 pages, 6 figure
Observation and study of the decay
We report the observation and study of the decay
using events
collected with the BESIII detector. Its branching fraction, including all
possible intermediate states, is measured to be
. We also report evidence for a structure,
denoted as , in the mass spectrum in the GeV/
region. Using two decay modes of the meson ( and
), a simultaneous fit to the mass spectra is
performed. Assuming the quantum numbers of the to be , its
significance is found to be 4.4, with a mass and width of MeV/ and MeV, respectively, and a
product branching fraction
. Alternatively, assuming , the
significance is 3.8, with a mass and width of MeV/ and MeV, respectively, and a product
branching fraction
. The angular distribution of
is studied and the two assumptions of the
cannot be clearly distinguished due to the limited statistics. In all
measurements the first uncertainties are statistical and the second systematic.Comment: 10 pages, 6 figures and 4 table
Observation of and confirmation of its large branching fraction
The baryonic decay is observed, and the
corresponding branching fraction is measured to be
, where the first uncertainty is statistical
and second systematic. The data sample used in this analysis was collected with
the BESIII detector operating at the BEPCII double-ring collider with
a center-of-mass energy of 4.178~GeV and an integrated luminosity of
3.19~fb. The result confirms the previous measurement by the CLEO
Collaboration and is of greatly improved precision, which may deepen our
understanding of the dynamical enhancement of the W-annihilation topology in
the charmed meson decays
Study of and and
We study the decays of and to the final states
and based on a single
baryon tag method using data samples of
and events collected with
the BESIII detector at the BEPCII collider. The decays to
are observed for the first time. The
measured branching fractions of and
are in good agreement with, and much
more precise, than the previously published results. The angular parameters for
these decays are also measured for the first time. The measured angular decay
parameter for , , is found to be negative, different to the other
decay processes in this measurement. In addition, the "12\% rule" and isospin
symmetry in the and and
systems are tested.Comment: 11 pages, 7 figures. This version is consistent with paper published
in Phys.Lett. B770 (2017) 217-22
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