The nuclear electric quadrupole moment (NQM) of ruthenium was reevaluated by means of the molecular method. Therefore, four-component relativistic electronic structure calculations of the electric field gradient at the Ru nucleus in ruthenium monocarbide, which were done with the coupled cluster methodology and carefully augmented large basis sets, were combined with the respective nuclear quadrupole coupling constant from experiments. This provided a recommended NQM value of (425 ± 13) mbarn for 101Ru.

Two new relativistic adapted Gaussian basis sets of small and medium size are presented for all elements from Hydrogen through Xenon. These sets are free of variational prolapse and were developed with the polynomial generator coordinate Dirac‐Fock method to be used with two finite nuclear models, uniform sphere and Gaussian. The largest basis set errors for electronic configurations from the Aufbau principle are around 10.0 and 4.7 mHartree for the small– and medium–size sets, respectively, which is in accordance with the accuracy level expected in each case. Hence, to our knowledge, these are the smallest prolapse free basis sets developed for these elements.

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