Ab initio calculations of Ca III Stark broadening parameters,transition probabilities and radiative lifetimes

Abstract

We have determined matrix elements for all experimental configurations of Ca III, including
the 3s3p63d configuration. These values have been obtained using intermediate coupling (IC).
For these IC calculations, we have used the standard method of least-squares fitting from
the experimental energy levels, using the computer code developed by Robert Cowan. In this
paper, using these matrix elements, we report the calculated values of the Ca III Stark widths
and shifts for 148 spectral lines, of 56 Ca III spectral line transition probabilities and of eight
radiative lifetimes of Ca III levels. The Stark widths and shifts, calculated using the Griem
semi-empirical approach, correspond to the spectral lines of Ca III and are presented for an
electron density of 1017 cm?3 and temperatures T = 1.0?10.0 (×104 K). The theoretical trends
of the Stark broadening parameter versus the temperature are presented for transitions that
are of astrophysical interest. There is good agreement between our calculations, for transition
probabilities and radiative lifetimes, and the experimental values presented in the literature.
We have not been able to find any values for the Stark parameters in the references.