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SUMMARY:Accurate calculations of atomic data for He-like oxygen
DTSTART;VALUE=DATE-TIME:20200731T113000Z
DTEND;VALUE=DATE-TIME:20200731T113300Z
DTSTAMP;VALUE=DATE-TIME:20200925T100534Z
UID:indico-contribution-356236-3814680@indico.cern.ch
DESCRIPTION:Speakers: Dhia Elhak Salhi (CNSTN)\nIn the last few years\, va
rious theoretical and experimental research for providing atomic data for
He-like ions have been carried out. For our calculations of atomic data fo
r He-like oxygen\, we have adopted the Multiconfigurational-Dirac-Hartree-
Fock (MCDHF) method implemented in the General-Purpose Relativistic Atomic
Structure Package (GRASP2K) code. Further relativistic corrections arisin
g from the Breit interaction and QED effects have also been included. Addi
tionally\, in order to make a rigorous accuracy assessment of our results\
, we have also performed calculations by using the Many Body Perturbation
Theory (MBPT) method implemented in the Flexible Atomic Code (FAC) of Gu.
\nThe accuracy of the present calculations is high enough to facilitate id
entification of many observed spectral lines. There are required in the st
udy of high-temperature plasmas such as those occurring in fusion energy r
esearch and in astrophysical research.\n\nhttps://indico.cern.ch/event/868
940/contributions/3814680/
LOCATION:virtual conference
URL:https://indico.cern.ch/event/868940/contributions/3814680/
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SUMMARY:Many Body Perturbation Theory of energy levels\, wavelengths\, osc
illator strengths\, radiative rates and lifetimes of He-like Lithium
DTSTART;VALUE=DATE-TIME:20200731T113500Z
DTEND;VALUE=DATE-TIME:20200731T113800Z
DTSTAMP;VALUE=DATE-TIME:20200925T100534Z
UID:indico-contribution-356236-3814696@indico.cern.ch
DESCRIPTION:Speakers: Soumaya Manai (National Centre for Nuclear Sciences
and Technologies (CNSTN)\, Tunisia)\nIn recent years\, there have been ext
ensive spectroscopic studies\, both experimental and theoretical\, of heli
um isoelectronic sequence. Such an analysis requires information for a wid
e range of atomic parameters\, including energy levels\, wavelengths\, osc
illator strengths\, radiative rates and lifetimes. Our aim was to provide
a set of accurate energy levels\, wavelengths\, oscillator strengths\, ra
diative rates and lifetimes for helium-like ions. Accurate energy levels c
alculations among the lowest 71 levels arising of $1s^{2}$ and $1snl$ ($n\
\leq6$\, $l\\leq(n-1)$) configurations of He-like lithium are carried out
through the standard relativistic configuration interaction $(RCI)$ approa
ch\, the second-order many body perturbation theory $(MBPT)$ [1]. The calc
ulation methods are derived by a modified self-consistent Dirac-Fock-Slate
r iteration. We have also considered relativistic effects by incorporating
quantum electrodynamics (QED) and Breit corrections. We provide accurate
calculations of energy levels\, wavelengths\, radiative rates and lifetime
s of all types of transitions ($E1$\, $E2$\, $M1$ and $M2$) for He-like li
thium. The use of the $MBPT$ approach significantly improves the value of
the energy levels. The maximum difference relative to the NIST data [2] be
comes $651\\: cm^{-1}$ while the majority of values of energy levels of $R
CI$ method are decreased by approximately $5000 \\:cm^{-1}$. The average
relative deviation don't exceed $5\\%$ for the three methods compared to
the results from NIST. For the MBPT calculations we have $-0.47\\pm 0.90\\
%$\, for the RCI calculations we have $2.62\\pm 1.70\\%$ and for the sta
ndard FAC calculations we have $3.13\\pm 1.60\\%$. The present results are
in good agreement with already published data in the literature (theoreti
cal [3] and experimental data). Several new energy levels were found out w
here no other theoretical or experimental results are available. We expect
that our extensive calculations will be useful to experimentalists for id
entifying the fine-structure levels [4].\n[1] MF. Gu\, Canadian Journal of
Physics\, 86\, 675–689\, (2008).\n[2] Kramida\, A.\, Ralchenko\, Yu.\,
Reader\, J.\, and NIST ASD Team (2018). NIST Atomic Spectra Database (ver.
\n5.5.2)\, [Online]. Available: https://physics.nist.gov/asd [2018\, Febru
ary 20]. National Institute of Standards and Technology\, Gaithersburg\, M
D.\n[3] KM. Aggarwal\, T. Kato\, FP. Keenan\, I. Murakami\, Physica Script
a J\, 83\, 015302\, (2010).\n[4] A.M. Cantu\, W.H. Parkinson\, G. Tondello
and G.P. Tozzi\, Opt. Soc. Am J. 67\, 1030-1033\, (1977).\n\nhttps://indi
co.cern.ch/event/868940/contributions/3814696/
LOCATION:virtual conference
URL:https://indico.cern.ch/event/868940/contributions/3814696/
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