Theoretical study of the hyperfine interaction constants, Landé g-factors, and electric quadrupole moments for the low-lying states of the 61Ni q+ (q = 11,12,14, and 15) ions

Zhang, Tingxian; Zhang, Yonghui; Li, Chengbin; Shi, Ting-Yun

doi:10.1088/1674-1056/abc7a3

Cited by 3 publications

(1 citation statement)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Multiconfiguration methods, both non-relativistic multiconfiguration Hartree-Fock (MCHF) and relativistic multiconfiguration Dirac-Hartree-Fock (MCDHF), have been used for a long time to calculate hyperfine structure constants for a large number of states and elements of different complexities [5,6,[9][10][11]. Common to these calculations is the fact that they often show slow and irregular convergence patterns, requiring large orbital sets and large CSF expansions for obtaining accurate and reliable values of the hyperfine interaction constants [12].…”

Section: Introductionmentioning

confidence: 99%

Natural Orbitals and Targeted Non-Orthogonal Orbital Sets for Atomic Hyperfine Structure Multiconfiguration Calculations

Ma,

Li,

Godefroid

et al. 2024

Atoms

View full text Add to dashboard Cite

Hyperfine structure constants have many applications, but are often hard to calculate accurately due to large and canceling contributions from different terms of the hyperfine interaction operator, and also from different closed and spherically symmetric core subshells that break up due to electron correlation effects. In multiconfiguration calculations, the wave functions are expanded in terms of configuration state functions (CSFs) built from sets of one-electron orbitals. The orbital sets are typically enlarged within the layer-by-layer approach. The calculations are energy-driven, and orbitals in each new layer of correlation orbitals are spatially localized in regions where the weighted total energy decreases the most, overlapping and breaking up different closed core subshells in an irregular pattern. As a result, hyperfine structure constants, computed as expectation values of the hyperfine operators, often show irregular or oscillating convergence patterns. Large orbital sets, and associated large CSF expansions, are needed to obtain converged values of the hyperfine structure constants. We analyze the situation for the states of the {2s22p3,2s22p23p,2s22p24p} odd and {2s22p23s,2s2p4,2s22p24s,2s22p23d} even configurations in N I, and show that the convergence with respect to the increasing sets of orbitals is radically improved by introducing separately optimized orbital sets targeted for describing the spin- and orbital-polarization effects of the 1s and 2s core subshells that are merged with, and orthogonalized against, the ordinary energy-optimized orbitals. In the layer-by-layer approach, the spectroscopic orbitals are kept frozen from the initial calculation and are not allowed to relax in response to the introduced layers of correlation orbitals. To compensate for this lack of variational freedom, the orbitals are transformed to natural orbitals prior to the final calculation based on single and double substitutions from an increased multireference set. The use of natural orbitals has an important impact on the states of the 2s22p23s configuration, bringing the corresponding hyperfine interaction constants in closer agreement with experiment. Relying on recent progress in methodology, the multiconfiguration calculations are based on configuration state function generators, cutting down the time for spin-angular integration by factors of up to 50, compared to ordinary calculations.

show abstract

Section: Introductionmentioning

confidence: 99%

Natural Orbitals and Targeted Non-Orthogonal Orbital Sets for Atomic Hyperfine Structure Multiconfiguration Calculations

Ma,

Li,

Godefroid

et al. 2024

Atoms

View full text Add to dashboard Cite

show abstract

Hyperfine-induced frequency shifts for the candidate clock transitions in the Ni12+61 ion

Zhang,

Li,

Shi

2024

Phys. Rev. A

View full text Add to dashboard Cite

Precision measurement of M1 optical clock transition in Ni12+

Chen,

Zhou,

et al. 2024

Phys. Rev. Research

View full text Add to dashboard Cite

Highly charged ions (HCIs) have drawn significant interest in quantum metrology and in the search for new physics. Among these, Ni12+ is considered as one of the most promising candidates for the next generation of HCI optical clocks, due to its two E1-forbidden transitions M1 and E2, which occur in the visible spectral range. In this work, we used the Shanghai-Wuhan electron beam ion trap to perform a high-precision measurement of the M1 transition wavelength. Our approach involved an improved calibration scheme for the spectra, utilizing auxiliary Ar+ lines for calibration and correction. Our final measured result of the M1 transition wavelength demonstrates a fivefold improvement in accuracy compared to our previous findings, reaching the subpicometer level accuracy. In combination with our rigorous atomic-structure calculations to capture the electron correlations and relativistic effects, the quantum electrodynamic corrections were extracted. Published by the American Physical Society 2024

show abstract

Theoretical study of the hyperfine interaction constants, Landé g-factors, and electric quadrupole moments for the low-lying states of the ⁶¹Ni^q+ (q = 11,12,14, and 15) ions

Cited by 3 publications

References 39 publications

Natural Orbitals and Targeted Non-Orthogonal Orbital Sets for Atomic Hyperfine Structure Multiconfiguration Calculations

Natural Orbitals and Targeted Non-Orthogonal Orbital Sets for Atomic Hyperfine Structure Multiconfiguration Calculations

Hyperfine-induced frequency shifts for the candidate clock transitions in the Ni12+61 ion

Precision measurement of M1 optical clock transition in Ni12+

Contact Info

Product

Resources

About