ELECTRON IMPACT EXCITATION COLLISION STRENGTHS FOR EXTREME ULTRAVIOLET LINES OF Fe VII

• Published in: The Astrophysical journal Vol. 788; no. 1; pp. 1 - 11
• Main Authors: Tayal, S S, ZATSARINNY, O
• Format: Journal Article
• Language: English
• Published: United States 10-06-2014
• Subjects: ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATOMIC AND MOLECULAR PHYSICS; Collision dynamics; COLLISIONS; CONFIGURATION; COUPLING; DISTRIBUTION; Electron impact excitation; ELECTRON TEMPERATURE; ENERGY LEVELS; EXCITATION; EXPANSION; EXTREME ULTRAVIOLET RADIATION; FINE STRUCTURE; HARTREE-FOCK METHOD; IRON; Mathematical analysis; OSCILLATOR STRENGTHS; R MATRIX; Strength; TRANSFORMATIONS; Ultraviolet; VELOCITY; WAVE FUNCTIONS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/788/1/24

Extensive calculations have been performed for electron impact excitation collision strengths and oscillator strengths for the Fe VII extreme ultraviolet lines of astrophysical importance. The collision strengths for fine-structure transitions are calculated in the B-spline Breit-Pauli R-matrix approach. The target wavefunctions have been calculated in the multiconfiguration Hartree-Fock method with term-dependent non-orthogonal orbitals. The close-coupling expansion includes 189 fine-structure levels of Fe VII belonging to terms of the ground 3p super(6)3d super(2) and excited 3p super(5)3d super(3), 3p super(6)3d4 l, 3p super(6)3d5 s, and 3p super(6)3d5 p configurations. The effective collision strengths are determined from the electron excitation collision strengths by integration over a Maxwellian distribution of electron velocities. The effective collision strengths are provided for 17766 fine-structure transitions at electron temperatures from 10 super(4) to 10 super(7) K. Our results normally agree with the previous R-matrix frame-transformation calculations by Witthoeft & Badnell. However, there are important differences for some transitions with the previous calculations. The corrections to the previous results are mainly due to more extensive expansions for the Fe VII target states.