Ab initio state-dependent multiconfiguration Dirac-Fock calculations of the electron density at the nucleus for low-lying states in the 4f115d6s2 Er I configuration

The authors have performed ab initio multiconfiguration Dirac-Fock (MCDF) calculations of the electron density at the nucleus for all states belonging to the four lowest-lying terms of the 4f115d6s2 configuration in Er I. From a comparison with recent experimental optical isotope shift data for the two lowest lying terms within this manifold, the authors discuss the validity of the state-dependent ab initio MCDF approach to electron density calculations.