Atomic data benchmarked by Large-scale Multiconfiguration Dirac-Hartree-Fock Calculations for Beryllium

Abstract

The multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods are used to provide excitation energies, radiative transition data, lifetimes, Lande g-factors, hyperfine interaction constants and isotope shift parameters for the 99 lowest levels of configurations 1s^22snl (n <= 7) + 1s^22p^2 in beryllium. Compared with available experimental excitation energies, the average difference with the standard deviation is 7.08 +/- 1.14cm^-1 (0.011% +/- 0.003%), which demonstrates the excellent theory-observation agreement. The uncertainties of the transition rates are estimated based on two independent methods. The present MCDHF/RCI oscillator strengths and those obtained from the explicitly correlated Gaussian (ECG) method all agree within 2%, except for four transitions affected by strong cancellation effects. For lifetimes, hyperfine splittings and isotope shifts, the present MCDHF/RCI results show good agreement with the few available experimental values, supporting the reliability of our predictions for many states lacking experimental measurements. These comprehensive results can be used in line identification and diagnostics of astrophysical plasmas.

Figures (7)

• Figure 1: Difference (in $\rm{cm^{-1}}$) of the MCDHF/RCI excitation energies for the $1s^2 2s 2p~^{3}P_{0}^{\circ}$, $1s^2 2s 2p~^{1}P_{1}^{\circ}$, $1s^2 2s 3s~^{1}S_{0}$, $1s^2 2p^2~^{1}D_{2}$ levels as a function of AS. MR is set as $\rm{MR_0}$.
• Figure 2: Difference (in $\rm{cm^{-1}}$) of the MCDHF/RCI excitation energies for the $1s^2 2s 2p~^{3}P_{0}^{\circ}$, $1s^2 2s 2p~^{1}P_{1}^{\circ}$, $1s^2 2s 3s~^{1}S_{0}$, $1s^2 2p^2~^{1}D_{2}$ levels as a function of MR. AS is set as $\rm{AS_{15}}$.
• Figure 3: Effects (in $\rm{cm^{-1}}$) of extending the MR on $\delta S$ for the transitions of $1s^2 2s 4p~^{1}P_{1}^{\circ} - 1s^2 2s^2~^{1}S_{0}$, $1s^2 2s 5p~^{1}P_{1}^{\circ} - 1s^2 2s 4s~^{1}S_{0}$, $1s^2 2s 6p~^{1}P_{1}^{\circ} - 1s^2 2s 5s~^{1}S_{0}$, $1s^2 2s 7p~^{1}P_{1}^{\circ} - 1s^2 2s 6s~^{1}S_{0}$. AS is set as $\rm{AS_{15}}$.
• Figure 4: The difference $\delta S$ for E1 transitions with BF $\geq 10^{-5}$ among the lowest 99 $n \leq 7$ levels.
• Figure 5: Distribution of line strength $S$ as a function of the $G_{S=0}$ parameter for E1 transitions with BF $\geq 10^{-5}$ among the 99 levels. Different colours mark the accuracy class of estimated transitions based on the methodology described in Rynkun.2022.p82. Black colour means AA accuracy class, red - A+, green - A, blue - B+, cyan - B, magenta - C+, orange - C, purple - E.