MCDHF calculations of isotope shifts in neutral antimony

Abstract

a b s t r a c tAb initio multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations have been carried out in order to determine the isotope shift (IS) electronic parameters of transitions belonging to electric dipole (E1) transition arrays 5s 2 5p 3 − 5s 2 5p 2 6s , 5s 2 5p 2 6s − 5s 2 5p 2 6p and 5s 2 5p 2 6s − 5s 2 5p 2 7p in neutral antimony, Sb I. In a correlation model limited to single and double excitations from the valence shells, these parameters, combined with the changes in mean-square nuclear charge radius δ r 2 123,121 compiled by Angeli and Marinova [3] produce isotope shifts values in good agreement with the most recent measurements by high-resolution emission and optogalvanic absorption spectroscopy of Sobolewski et al. [5] but not with the old measurements of Buchholz et al. [4] for 5p 3 − 5p 2 6s . However, our analysis does not allow to reject the latter due to the large uncertainty affecting δ r 2 123,121 , i.e. 0.072 ± 0.048 fm 2 [3]. This shows the need of a more accurate determination of this nuclear parameter. Although improving excitation energies, the inclusion of core-valence correlation limited to one hole in the 4d core subshell destroyed the theory-experiment agreement on the IS parameters.

Electronic isotope shift factors for the Ir 5d76s24F9/2Schiffmann1, Godefroid2 2021Journal of Quantitative Spectroscopy and Radiative Transfer6100View full textAdd to dashboardCite

“…as it was done [14][15][16][17] using the RIS3 program [18] designed as a module of the Grasp2K atomic structure package [19] .…”

“…We expect these three configurations to have significantly different electronic densities at the origin, according to their respective occupation number of the s orbitals [30] . Thanks to a simple occupation number-based analysis, we expect the following inequalities ρ(5 d 8 6 p) < ρ(5 d 7 6 s 6 p) < ρ(5 d 6 6 s 2 6 p) (14) to hold, in which the density increases with the occupation number of the 6 s orbital. Independent Dirac-Fock calculations for each configuration, assuming a common [Xe]4 f 14 core, confirm our intuitions since the computed electron densities, relative to the lowest value, are, in units of a −1 0 , ρ(5…”

Isotope shifts for ${}^1S_0-{}^3P_{0,1}^o$ Yb lines from multi-configuration Dirac-Hartree-Fock calculations

“…These values differ on average by 11.5% when compared with measured values from [72]. This difference may reduce with the inclusion of deeper core-valence correlations and possibly core-core correlations [28,48,68]. Variation in nuclear deformation between the isotopes, not accounted for in these computations, may also contribute to the differ-ences between the experimental and computational isotope shifts.…”

“…Advents in modern computing allow for relativistic atomic structure calculations to be performed with results consistent with experimentally determined values to a few parts in 10 5 [21][22][23][24]. Such computations are also used to determine mass and field shift parameters of isotope shifts for King plot analyses [4,10,[25][26][27][28][29]. Low-lying energy levels in ytterbium have been explored through computational means [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], however they do not compute isotopes separately and often avoid the 3 P o 0 state.…”

Electronic isotope shift factors for the Ir $5d^{7}6s^{2} \ ^{4}\!F_{9/2} \to (\mbox{odd},J= 9/2)$ line at 247.587 nm

“…We expect these three configurations to have significantly different electronic densities at the origin, according to their respective occupation number of the s orbitals [30]. Thanks to a simple occupation number-based analysis, we expect the following inequalities ρ(5d 8 6p) < ρ(5d 7 6s6p) < ρ(5d 6 6s 2 6p) (14) to hold, in which the density increases with the occupation number of the 6s orbital. Independent Dirac-Fock calculations for each configuration, assuming a common [Xe]4f 14 core, confirm our intuitions since the computed electron densities, relative to the lowest value, are, in units of a −1 0 , ρ(5d 8 6p) = 0 < ρ(5d 7 6s6p) = 103 < ρ(5d 6 6s 2 6p) = 230.…”