Multireference Møller–Plesset perturbation theory results on levels and transition rates in Al-like ions of iron group elements

Abstract

Ground configuration and low-lying levels of Al-like ions contribute to a variety of laboratory and solar spectra, but the available information in databases are neither complete nor necessarily correct. We have performed multireference Møller-Plesset perturbation theory calculations that approach spectroscopic accuracy in order to check the information that databases hold on the 40 lowest levels of Al-like ions of iron group elements (K through Ge), and to provide input for the interpretation of concurrent experiments. Our results indicate problems of the database holdings on the levels of the lowest quartet levels in the lighter elements of the range studied. The results of our calculations of the decay rates of five long-lived levels (3s 2 3p 2 P o 3/2 , 3s3p 2 4 P o J and 3s3p3d 4 F o 9/2 ) are compared with lifetime data from beam-foil, electron beam ion trap and heavy-ion storage ring experiments.

Transition probabilities and oscillator strengths of E1 transitions in Fe XII and Fe XIV

“…Generally there is a very good agreement between the two calculations except for a few highly excited levels. The lifetimes for the 3s3p 2 4 P 5/2,3/2,1/2 levels have also been calculated by Santana et al [23] in MR-MP calculations and they reported 44.3, 168 and 32.3 ns lifetimes for the 4 P 5/2 , 4 P 3/2 and 4 P 1/2 levels respectively.…”

“…Huang [20,21] calculated radiative rates in the multiconfiguration Dirac-Fock method. The energy levels and lifetimes were also calculated in multireference Mollar-Plesset (MR-MP) perturbation theory [22,23]. The transition rates for electric quadrupole and magnetic dipole and quadrupole forbidden transitions in Fe XII and Fe XIV ions have been calculated using non-orthogonal orbitals in the MCHF approach by Tayal [24] where a comparison with the available theoretical and measured results for the forbidden transitions can be found.…”

Critical Assessment of Theoretical Calculations of Atomic Structure and Transition Probabilities: An Experimenter’s View

“…At lower Z one might expect that all relatively low-lying levels of Al-like ions are known. Santana et al [198] have calculated (using the MR-MP formalism) the lowest 40 levels of Al-like ions in the iron group (K (Z = 19) through Ge (Z = 32)) and compared the results with the NIST data base. For elements from Ti through Ni, almost all of the levels of the 3s 2 3p, 3s3p 2 , 3s 2 3d, 3p 3 , and 3s3p3d configurations were already known, whereas at a little lower or higher Z, the knowledge was and is rather patchy.…”

“…The computational result provided by Huang [67] coincides with experiment as well, but by comparison with other atomic systems one has to conclude that these computations are not accurate enough to call this more than a chance agreement. (Figure adapted from Figure 1 of [198], which includes a list of all the references.) 46…”

Relativistic MR-MP Energy Levels for L-shell Ions of Sulfur and Argon

“…The MR-MP method has been shown to yield highly accurate valence level energies (Vilkas et al 2005; Santana et al 2009; Santana & Tr¨abert 2015; Santana 2016) as well as core-excited level energies (Beiersdorfer et al 2013; Díaz et al 2013; Beiersdorfer et al 2017). We recently applied (Santana et al 2018) this method to calculate both valence and K-vacancy level energies in L-shell ions Si V - Si XII.…”