Calculated transition strengths and experimental isotope shifts in neutral californium

This database contains calibrated atomic structure data of neutral californium. Details of the atomic structure calculations can be found in the publication: Berndt et al., 'Optical spectroscopy of 253,254Cf near the N = 152 neutron shell: implications for kilonova spectra, submitted to Physical Review Letters (2026). Content: Calibrated energy levels Calibrated E1 transitions Calibrated M1 transitions Calibrated E2 transitions Transitions used for the isotope shift analysis Sample file content: energy levels The header provides details on the total number of energy levels located below the ionisation threshold, along with the number of experimentally known levels that were successfully identified in our computations. Additionally, it specifies the total number of electronic configurations considered, irrespective of whether their associated levels lie below the ionisation threshold. Spectroscopic LS terms were determined using the JJ2LSJ code (G. Gaigalas, C. Fischer, P. Rynkun, and P. Jönsson, 'Transformation and Unique Labeling for Energy Levels', Atoms 5, 6 (2017)). For each energy level, we indicate whether it was calibrated to experimental energies ("xmatch"), adjusted by applying a global shift derived from the bulk properties of its corresponding J-parity group ("shifted"), or left uncalibrated ("uncalib") in cases where no energy correction was applied (see Flörs et al., 'Calibrated lanthanide atomic data for kilonova radiative transfer: Atomic structure and opacities, Physical Review D, Volume 113, Issue 6, id.063041, 51 pp. (2026) for details). Energy levels of Cf ITitle: Optical spectroscopy of 253,254Cf near the N = 152 neutron shell: implications for kilonova spectraAuthors: Berndt S., et al.FAC calculations conducted by: Floers A.Number of levels: 1068Number of xmatch levels: 150Number of configurations: 8--------------------------------------------------------------------------------- Column Name Unit Description --------------------------------------------------------------------------------- Index ---- Number of energy level sorted by energy Z ---- Atomic number Charge ---- Ion charge Energy cm-1 Energy of energy level J ---- Angular momentum Parity ---- Parity: 0 = even, 1 = odd Configuration ---- Leading order configuration LS ---- Leading order LS term Method ---- Calibration method: uncalib / shifted / xmatch--------------------------------------------------------------------------------- Index Z Charge Energy J Parity Configuration LS Method 0 98 0 0.00 8 0 5f10.7s2 5I xmatch 1 98 0 8516.38 5 0 5f10.7s2 5F xmatch 2 98 0 9078.14 7 0 5f10.7s2 5I xmatch 3 98 0 10589.25 2 0 5f10.7s2 3P xmatch 4 98 0 11074.39 6 0 5f10.7s2 5I xmatch 5 98 0 13965.75 4 0 5f10.7s2 5F xmatch 6 98 0 15375.47 4 0 5f10.7s2 5I xmatch 7 98 0 15846.14 5 0 5f10.7s2 5I xmatch 8 98 0 16820.39 6 0 5f10.7s2 5G xmatch 9 98 0 16909.54 8 1 5f9.6d1.7s2 7H xmatch Sample file content: calibrated E1 transitions The transition files provide data on radiative transitions between computed energy levels, including both experimentally matched and theoretically predicted states. Summary statistics indicate the total number of transitions, as well as the subset for which one or both participating levels were identified through experimental calibration. For each transition, the dataset includes the indices and properties of the lower and upper levels, such as energy, total angular momentum (J), parity, leading electronic configuration, and dominant LS term. The calibration status of each level is recorded as either directly matched to experimental energies ("xmatch"), adjusted via global shifts within J-parity groups ("shifted"), or left uncalibrated ("uncalib"). Each transition is further characterized by its type (E1 for all transitions in this work), transition energy, wavelength, the logarithm of the weighted oscillator strength (log gf), and the Einstein A-value (A) representing the spontaneous radiative decay rate. Transitions of Cf IAuthors: Berndt S., et al.Title: Optical spectroscopy of 253,254Cf near the N = 152 neutron shell: implications for kilonova spectraFAC calculations conducted by: Floers A.Total number of transitions: 48402Total number of transitions with both upper and lower xmatch level: 1589Total number of transitions with either upper or lower xmatch level: 13592--------------------------------------------------------------------------------- Column Name Unit Description --------------------------------------------------------------------------------- Lower ---- Index of the lower level E_Lower cm-1 Energy of the lower level J_Lower ---- Angular momentum of the lower level P_Lower ---- Parity of the lower level: 0 = even, 1 = odd Config_Lower ---- Leading order configuration of the lower level LS_Lower ---- Leading order LS term of the lower level Method_Lower ---- Lower level calibration method: uncalib / shifted / xmatch Upper ---- Index of the upper level E_Upper cm-1 Energy of the upper level J_Upper ---- Angular momentum of the upper level P_Upper ---- Parity of the upper level: 0 = even, 1 = odd Config_Upper ---- Leading order configuration of the upper level LS_Upper ---- Leading order LS term of the upper level Method_Upper ---- Upper level calibration method: uncalib / shifted / xmatch Type ---- Transitions type: E1 / M1 / E2 E_Transition cm-1 Transition energy WV_Transition A Transition wavelength Log(gf) ---- log10 of the weighted oscillator strength gf A s-1 Radiative transition rate / Einstein A-value--------------------------------------------------------------------------------- Lower E_Lower J_Lower P_Lower Config_Lower LS_Lower Method_Lower Upper E_Upper J_Upper P_Upper Config_Upper 0 0.00 8 0 5f10.7s2 5I xmatch 9 16909.54 8 1 5f9.6d1.7s2 0 0.00 8 0 5f10.7s2 5I xmatch 10 17308.17 7 1 5f9.6d1.7s2 0 0.00 8 0 5f10.7s2 5I xmatch 11 17459.21 8 1 5f10.7s1.7p1 0 0.00 8 0 5f10.7s2 5I xmatch 14 18483.06 9 1 5f10.7s1.7p1 0 0.00 8 0 5f10.7s2 5I xmatch 17 19303.06 8 1 5f10.7s1.7p1 0 0.00 8 0 5f10.7s2 5I xmatch 18 19322.22 7 1 5f10.7s1.7p1 0 0.00 8 0 5f10.7s2 5I xmatch 20 19907.47 9 1 5f9.6d1.7s2 0 0.00 8 0 5f10.7s2 5I xmatch 33 23060.37 8 1 5f9.6d1.7s2 0 0.00 8 0 5f10.7s2 5I xmatch 34 23093.35 9 1 5f10.7s1.7p1LS_Upper Method_Upper Type E_Transition WV_Transition Log(gf) A 7H xmatch E1 16909.54 5913.82 -0.8620 1.5415e+06 7H xmatch E1 17308.17 5777.62 -0.5980 3.3615e+06 7H xmatch E1 17459.21 5727.64 -0.9473 1.3503e+06 7I xmatch E1 18483.06 5410.36 -0.2391 6.9156e+06 3K xmatch E1 19303.06 5180.52 -0.4918 4.7116e+06 5H xmatch E1 19322.22 5175.39 -0.5090 5.1428e+06 7I xmatch E1 19907.47 5023.24 0.2145 2.2798e+07 7H xmatch E1 23060.37 4336.44 -0.0041 2.0668e+07 7I xmatch E1 23093.35 4330.25 -0.5734 5.0003e+06 Sample file content: Transitions used for the isotope shift analysis We also provide a dataset with a particular focus on field shifts, including a total of 19 transitions and is based on both multiconfiguration Dirac–Hartree–Fock (MCDHF) and configuration interaction (CI) calculations. For each transition, the properties of the lower and upper levels are listed, including their energies, total angular momentum (J), parity, and, if available, leading electronic configuration. The lower level corresponds to the ground state, while upper-level energies are provided from both MCDHF and CI calculations where available. Field shift parameters (in GHz fm^{-2}) are reported for both computational approaches, quantifying the sensitivity of each transition to changes in the nuclear charge radius. Transitions of Cf ITitle: Optical spectroscopy of 253,254Cf near the N = 152 neutron shell: implications for kilonova spectraAuthors: Berndt S., et al.MCDHF calculations conducted by: Andrews J. S. and Bieron J.CI calculations conducted by: Bondarev A.Total number of transitions: 19--------------------------------------------------------------------------------- Column Name Unit Description --------------------------------------------------------------------------------- E_Lower cm-1 Energy of the lower level J_Lower ---------- Angular momentum of the lower level P_Lower ---------- Parity of the lower level: 0 = even, 1 = odd Config_Lower ---------- Leading order configuration of the lower level LS_Lower ---------- Leading order LS term of the lower level E_Upper_MCDHF cm-1 Energy of the upper level (MCDHF calculation) E_Upper_CI cm-1 Energy of the upper level (CI calculation) J_Upper ---------- Angular momentum of the upper level P_Upper ---------- Parity of the upper level: 0 = even, 1 = odd Config_Upper ---------- Leading order configuration of the upper level Type ---------- Transitions type: E1 / M1 / E2 WV_Transition_MCDHF A Transition wavelength (MCDHF calculation) WV_Transition_CI A Transition wavelength (CI calculation) shift_MCDHF GHz * fm-2 Field shift (MCDHF calculation) shift_CI GHz * fm-2 Field shift (CI calculation) A_MCDHF s-1 Radiative transition rate / Einstein A-value (MCDHF calculation) A_CI s-1 Radiative transition rate / Einstein A-value (CI calculation)---------------------------------------------------------------------------------E_Lower J_Lower P_Lower Config_Lower LS_Lower E_Upper_MCDHF E_Upper_CI J_Upper P_Upper Config_Upper 0.00 8 0 5f10.7s2 5I 17308 7 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 18483 9 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 20671 9 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 24081 21836 9 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 24564 7 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 24610 9 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 24911 7 1 unclear 0.00 8 0 5f10.7s2 5I 26851 7 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 28708 20978 7 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 29098 22062 7 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 31065 7 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 31456 9 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 31464 7 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 32219 7 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 32781 9 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 33767 9 1 5f10.7p1.7s1 0.00 8 0 5f10.7s2 5I 37349 9 1 5f9.6d1.7s2 0.00 8 0 5f10.7s2 5I 40476 9 1 unclear 0.00 8 0 5f10.7s2 5I 40612 9 1 5f10.7p1.7s1Type WV_Transition_MCDHF WV_Transition_CI shift_MCDHF shift_CI A_MCDHF A_CI E1 5777.68 33 4.22e+05 E1 5410.37 35 2.92e+04 E1 4837.70 -77 7.65e+05 E1 4152.65 4579.59 35 91 7.54e+04 2.50e+06 E1 4071.00 -70 4.39e+04 E1 4063.39 -80 8.01e+05 E1 4014.29 27 8.18e+04 E1 3724.26 32 6.52e+05 E1 3483.35 4766.89 -81 -84 2.83e+05 1.74e+06 E1 3436.66 4532.89 24 75 2.49e+05 1.68e+07 E1 3219.06 -6 1.22e+05 E1 3179.04 31 4.05e+06 E1 3178.24 -36 1.73e+05 E1 3103.76 35 2.62e+05 E1 3050.55 -62 1.36e+08 E1 2961.47 -80 9.38e+07 E1 2677.45 35 2.35e+04 E1 2470.60 -59 3.27e+04 E1 2462.33 18 1.60e+05 Acknowledgements: This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Heavy Elements Chemistry Program, under Award No. DE-FG02-13ER16414. The 253,254Cf isotopes used in this research were supplied by ILL Grenoble, with pre-products delivered by the U.S. DOE Isotope Program, managed by the Office of Science. This work has been supported by the Bundesministerium für Bildung und Forschung (BMBF, Germany) under Grant No. 05P18UMCIA. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 861198-LISA-H2020-MSCA- ITN-2019 and 885281-KILONOVA. This work has been supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Project-ID 279384907 - SFB 1245, and MA 4248/3-1.