The electron affinity of Po: a theoretical electron correlation study

Abstract

The electron affinity (EA) of polonium (Po) is calculated with the multiconfiguration Dirac-Hartree-Fock (MCDHF) method combined with a relativistic configuration-interaction (RCI) approach. Po is of particular interest as one of the few remaining elements with no experimental value for its EA. There are also relatively few theoretical studies for Po, targeting these properties. The latest calculation using MCDHF is over 10 years old and newer coupled-cluster studies indicate that this value is underestimating the EA. Earlier this year, a proposal was made to CERN to perform measurements on the EA of Po and it is expected that these experiments will take place in the foreseeable future. Hence, it is now important to analyze the discrepancy between the theoretical results by testing new MCDHF atomic structure correlation models. This work also serves as a preparatory study for future calculations of the isotope shift (IS) of the EA of Po. The IS in turn directly relates to the nuclear structure of Po. The results from the present study are compared to the prior theoretical estimates of the EA and the difficulties with treating and balancing correlation in Po and Po− will be discussed. The calculations performed estimates the EA to be 1.446 eV.