Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2009-10-28
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
6 figures, 5 tables within text, 2 electronic tables
Scientific paper
Aims. This work reports radiative transition rates and electron impact excitation collision strengths for levels of the 3s23p, 3s3p2, 3s24s, and 3s23d configurations of Siii. Methods. The radiative data were computed using the Thomas-Fermi-Dirac-Amaldi central potential, but with the modifications introduced by Bautista (2008) that account for the effects of electron-electron interactions. We also introduce new schemes for the optimization of the variational parameters of the potential. Additional calculations were carried out with the Relativistic Hartree-Fock and the multiconfiguration Dirac-Fock methods. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects. Results. We present extensive comparisons between the results of different approximations and with the most recent calculations and experiment available in the literature. From these comparisons we derive a recommended set of gf- values and radiative transition rates with their corresponding estimated uncertainties. We also study the effects of different approximations in the representation of the target ion on the electron-impact collision strengths. Our most accurate set of collision strengths were integrated over a Maxwellian distribution of electron energies and the resulting effective collision strengths are given for a wide range of temperatures. Our results present significant differences from recent calculations with the B-spline non-orthogonal R-matrix method. We discuss the sources of the differences.
Arav Nahum
Badnell Nigel R.
Bautista Manuel A.
Dunn Jennifer
Palmeri Patrick
No associations
LandOfFree
Radiative transition rates and collision strengths for Si II does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Radiative transition rates and collision strengths for Si II, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiative transition rates and collision strengths for Si II will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-718500