Electronic structure investigations in support of atomic spectroscopy

Atomic spectroscopy can provide a wealth of information about the structure of the heaviest elements. Experiments on these elements are inherently challenging, due to their low production rates and short lifetimes; such experiments can greatly benefit from reliable theoretical support. Accurate predictions of transition energies are needed to plan measurements and to successfully detect targeted transitions, while avoiding broad wavelength scans.
Atomic electrons can also be used as sensitive probes of the nucleus. Electronic energy levels can shift (isotope shift) and split (hyperfine structure) depending on the size, shape and spin of the nucleus, and these small details can be measured. To extract nuclear properties from such measurements, theoretical calculations of isotope shift and hyperfine structure constants are needed.
In this work, electronic structure calculations of isotope shift and hyperfine structure factors were performed for silicon, scandium, germanium and bismuth. The theoretical predictions were used in collaboration with experimental groups to extract nuclear properties.
Additionally, we present (to the best of our knowledge, the first) predictions of hyperfine structure constants for the heaviest actinide lawrencium, motivated by future planned experiments.
On the side of theoretical development, next-generation basis sets were optimized for all the s elements up to radium, and all p elements up to oganesson. Use of these basis sets in combination with modern electronic structure methods will allow for higher accuracies and lower uncertainties than was previously possible in calculations on heavy atoms and molecules.