| Issue |
A&A
Volume 420, Number 2, June III 2004
|
|
|---|---|---|
| Page(s) | 763 - 768 | |
| Section | Atomic, molecular, and nuclear data | |
| DOI | https://doi.org/10.1051/0004-6361:20035719 | |
| Published online | 28 May 2004 | |
Atomic data from the iron project*
LV. Electron impact excitation of Ni II
Centro de Física, Instituto Venezolano de Investigaciones Científicas (IVIC), PO Box 21827, Caracas 1020A, Venezuela
Corresponding author: mbautist@ivic.ve
Received:
20
November
2003
Accepted:
26
February
2004
We study the effects of using a 
pseudo-orbital on the
collision strengths for electron impact excitations of forbidden
transitions in Niii computed in the close coupling approximation.
It is found that the resonance structures of the collision strengths
are quite sensitive to the way the pseudo-orbital is created.
Further, the close coupling expansion with a single 
orbital
does not converge, resulting in a poor representation of 
-electrons
auto-ionizing states. Much greater expansions are needed to properly
represent resonance structures in electron impact excitation calculations,
resulting in variations
of up to factors of two, with respect to previous computations,
in the Maxwellian averaged excitation rate
coefficients.
Key words: atomic data / line: formation / ISM: abundances / atomic processes / ISM: HII regions
© ESO, 2004
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