J/ApJ/787/2Effective 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 (SIMBAD/NED BibCode)ADC_Keywords: Atomic physicsKeywords: atomic data - atomic processesAbstract: 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 2s^{2}2p^{4}, 2s2p^{5}, 2p^{6}, 2s^{2}2p^{3}3s, 2s^{2}2p^{3}3p, 2s^{2}2p^{3}3d, and 2s2p^{4}3s 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).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) 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 2s^{2}2p^{4}, 2s2p^{5}, 2p^{6}, 2s^{2}2p^{3}3s, 2s^{2}2p^{3}3p, 2s^{2}2p^{3}3d, and 2s2p^{4}3s configurations of Si VII.File Summary:

FileName Lrecl Records Explanations

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

See also: J/A+AS/108/1 : IRON Project. V. O-like ions (Butler+, 1994)Byte-by-byte Description of file: table1.dat

Bytes Format Units Label Explanations

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

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)Note (3): MCHF calculations of Froese Fischer & Tachiev (2004, ADNDT, 87, 1); data from website http://nlte.nist.gov/MCHF/view.htmlNote (4): Superstructure calculation of Bhatia & Landi (2003ApJ...585..587B)Note (5): Superstructure calculations of Butler & Zeippen (1994, J/A+AS/108/1)

Byte-by-byte Description of file: table4.dat

Bytes Format Units Label Explanations

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

Byte-by-byte Description of file: table5.dat

Bytes Format Units Label Explanations

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

History: From electronic version of the journal(End)Prepared by [AAS], Tiphaine Pouvreau [CDS] 03-Aug-2017

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