Calculation of the hyperfine structure of Dy, Ho, Cf, and Es

A recently developed version of the configuration interaction (CI) method for open shells with a large number of valence electrons has been used to study two heavy atoms, californium (Cf, Z= 98) and einsteinium (Es, Z= 99). Motivated by experimental work to measure the hyperfine structure (HFS) for these atoms, we perform the calculations of the magnetic dipole HFS constants \(A\) and electric quadrupole HFS constant \(B\) for the sake of interpretation of the measurements in terms of nuclear magnetic moment \(\mu\) and electric quadrupole moment \(Q\). For verification of our computations, we have also carried out similar calculations for the lighter homologs dysprosium (Dy, Z= 66) and holmium (Ho, Z= 67), whose electronic structures are similar to Cf and Es, respectively. We have conducted a revision of the nuclear moments of some isotopes of Es leading to an improved value of the magnetic moment of \(^{253}\)Es [\(\mu\)(\(^{253}\)Es) = 4.20(13)\(\mu_N\)].