Analytic fits to the recommended electronimpact excitation and ionization cross sections for Be I are presented. The lowest 19 terms of configurations 2snl (n≤4) and 2p2 terms below the first ionization limit are considered. The fits are based on the accurate calculations with the convergent close coupling (CCC) method as well as the Bspline Rmatrix (BSR) approach. The fitted cross sections provide rate coefficients that are believed to approximate the original data within 10% with very few exceptions. The oscillator strengths for the dipoleallowed transitions between all the considered states are calculated with the relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) approach andmore »
This content will become publicly available on March 1, 2023
Generalizations of the RMatrix Method to the Treatment of the Interaction of ShortPulse Electromagnetic Radiation with Atoms
Since its initial development in the 1970s by Phil Burke and his collaborators, the Rmatrix theory and associated computer codes have become the method of choice for the calculation of accurate data for general electron–atom/ion/molecule collision and photoionization processes. The use of a nonorthogonal set of orbitals based on Bsplines, now called the Bspline Rmatrix (BSR) approach, was pioneered by Zatsarinny. It has considerably extended the flexibility of the approach and improved particularly the treatment of complex manyelectron atomic and ionic targets, for which accurate data are needed in many modelling applications for processes involving lowtemperature plasmas. Both the original Rmatrix approach and the BSR method have been extended to the interaction of short, intense electromagnetic (EM) radiation with atoms and molecules. Here, we provide an overview of the theoretical tools that were required to facilitate the extension of the theory to the time domain. As an example of a practical application, we show results for twophoton ionization of argon by intense shortpulse extreme ultraviolet radiation.
 Publication Date:
 NSFPAR ID:
 10317818
 Journal Name:
 Atoms
 Volume:
 10
 Issue:
 1
 ISSN:
 22182004
 Sponsoring Org:
 National Science Foundation
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