Relativistic R-matrix photoionization cross section calculations of Ne-like Co XVIII with resonance parameters

Abstract

We report total photoionization cross sections of the ground state and the first three excited states ( ) of Ne-like Co XVIII ion using the close-coupling Breit–Pauli R-matrix (BPRM) approximation. The target wavefunctions are constructed by configuration interaction technique (CIV3). Our calculated ionization threshold energies for the ground and excited states show a good agreement with the NIST ones. To further affirm the accuracy and reliability of our BPRM results, photoionization cross section calculations for the ground state have also been performed by employing the fully relativistic Dirac Atomic R-matrix Code. Our two independent calculations show a reasonable agreement both in magnitude and resonant photoionization cross sections. The resonance positions (Er), widths (Γ) and quantum defects (μ) due to ejection of a 2p or 2s electron from the ground state are given by adopting Quigley and Berrington method. We believe that our cross section data may be beneficial for the modelling and diagnostics of astrophysical plasmas.

Relativistic R-matrix calculations of the photoionization of W63+ ions

“…These resonant peaks fully or partially overlap with each other and are hardly distinguishable. In fact, this kind of resonance peak is very narrow and the corresponding Rydberg resonance series converges quickly to its excitation threshold [58]. From a theoretical point of view, the overlap of these resonant peaks is caused by a relativistic intermixing and coupling of the included channels [39].…”