J/ApJ/787/2 Effective collision strengths of Si VII (Sossah+, 2014)
Effective collision strengths for fine-structure transitions in Si VII.
Sossah A.M., Tayal S.S.
<Astrophys. J., 787, 2 (2014)>
=2014ApJ...787....2S 2014ApJ...787....2S (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: atomic data - atomic processes
Abstract:
The effective collision strengths for electron-impact excitation of
fine-structure transitions in Si VII are calculated as a function of
electron temperature in the range 5000-2000000 K. The B-spline
Breit-Pauli R-matrix method has been used to calculate collision
strengths by electron impact. The target wave functions have been
obtained using the multi-configuration Hartree-Fock method with
term-dependent non-orthogonal orbitals. The 92 fine-structure levels
belonging to the 46 LS states of 2s22p4, 2s2p5, 2p6, 2s22p33s,
2s22p33p, 2s22p33d, and 2s2p43s configurations are included
in our calculations of oscillator strengths and collision strengths.
There are 4186 possible fine-structure allowed and forbidden
transitions among the 92 levels. The present excitation energies,
oscillator strengths, and collision strengths have been compared with
previous theoretical results and available experimental data.
Generally, a good agreement is found with the 6 LS-state
close-coupling approximation results of Butler & Zeippen
(1994, J/A+AS/108/1) and the 44 LS-state distorted wave calculation of
Bhatia & Landi (2003ApJ...585..587B 2003ApJ...585..587B).
Description:
The purpose of present work is to calculate more accurate data for
Si VII by using highly accurate target descriptions and by including
a sufficient number of target states in the close-coupling expansion.
We also included fine-structure effects in the close-coupling
expansions to account for the relativistic effects. We used the
B-spline Breit-Pauli R-matrix (BSR) codes (Zatsarinny 2006CoPhC.174..273Z 2006CoPhC.174..273Z)
in our scattering calculations. The present method utilizes the
term-dependent non-orthogonal orbital sets for the description of the
target wave functions and scattering functions. The collisional and
radiative parameters have been calculated for all forbidden and
allowed transitions between the lowest 92 LSJ levels of 2s22p4, 2s2p5,
2p6, 2s22p33s, 2s22p33p, 2s22p33d, and 2s2p43s
configurations of Si VII.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 92 Comparison of Energy Levels and Lifetimes in
Si VII
table4.dat 98 1156 Wavelengths, Oscillator Strengths, and
Transition Probabilities for Electric Dipole
(E1) Transitions among LSJ Levels in Si VII
table5.dat 101 4186 Effective Collision Strengths for
Fine-Structure Transitions among the 92 LSJ
Levels of Si VII
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See also:
J/A+AS/108/1 : IRON Project. V. O-like ions (Butler+, 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Index [1/92] Index
4- 33 A30 --- Coupling CFG-LSJ coupling
35- 42 F8.5 Ry Ea Present excitation energy MCHF calculations
with 2665 configurations
44- 51 F8.5 Ry Eb Present excitation energy MCHF calculations
with 488 configurations
53- 60 F8.5 Ry EObs ? Observed excitation energy (1)
61 A1 --- n_EObs [*+] Note on Eobs (2)
63- 70 F8.5 Ry ECCF ? CCF excitation energy (3)
72- 79 F8.5 Ry EBHA ? BHA excitation energy (4)
81- 87 F7.5 Ry EBZ ? BZ excitation energy (5)
89- 95 E7.3 ns LifeP ? Present lifetime
97-103 E7.3 ns LifeCFF ? CFF lifetime
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Note (1): Observed energy levels from NIST (http://physics.nist.gov/PhysRefData)
Note (2): Notes as follows:
* = Observed energy levels from NIST and Kink & Engstroem (1997, PhyS, 56, 31)
+ = Observed energy levels from NIS and Kink et al. (1997ApJ...487..956K 1997ApJ...487..956K)
Note (3): MCHF calculations of Froese Fischer & Tachiev (2004, ADNDT, 87, 1);
data from website http://nlte.nist.gov/MCHF/view.html
Note (4): Superstructure calculation of Bhatia & Landi (2003ApJ...585..587B 2003ApJ...585..587B)
Note (5): Superstructure calculations of Butler & Zeippen (1994, J/A+AS/108/1)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 26 A26 --- i Initial Level
28- 53 A26 --- f Final Level
55 I1 --- gi [1/9] Initial level statistical weight
57- 58 I2 --- gf [1/11] Final level statistical weight
60- 68 F9.3 0.1nm Wave Wavelength in Angstroms
70- 78 E9.3 --- fL Length oscillator strength
80- 88 E9.3 --- fV Velocity oscillator strength
90- 98 E9.3 s-1 AL Transition probability
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- i [1/91] Initial level
4- 5 I2 --- f [2/92] Final level
7- 13 E7.2 --- CS0.5 Effective collision strength at 5000 K
15- 21 E7.2 --- CS1 Effective collision strength at 10000 K
23- 29 E7.2 --- CS2.5 Effective collision strength at 25000 K
31- 37 E7.2 --- CS5 Effective collision strength at 50000 K
39- 45 E7.2 --- CS7.5 Effective collision strength at 75000 K
47- 53 E7.2 --- CS10 Effective collision strength at 100000 K
55- 61 E7.2 --- CS20 Effective collision strength at 200000 K
63- 69 E7.2 --- CS40 Effective collision strength at 400000 K
71- 77 E7.2 --- CS60 Effective collision strength at 600000 K
79- 85 E7.2 --- CS80 Effective collision strength at 800000 K
87- 93 E7.2 --- CS100 Effective collision strength at 1000000 K
95-101 E7.2 --- CS200 Effective collision strength at 2000000 K
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 03-Aug-2017