Strengths and weaknesses of relativistic atomic structure calculations

Abstract

Among the relativistic atomic structure theories developed in the last two decades, two methods - multiconfiguration Dirac-Fock (MCDF) and relativistic many-body perturbation theory (RMBPT) - have extensively been applied to calculate spectroscopic properties of neutral atoms as well as highly charged ions. The strengths and weaknesses of these methods are discussed with some examples. The MCDF method is based on the shell structure familiar to atomic physicists, and hence intuitively easier to understand. On the other hand, the RMBPT method is more systematic in introducing correlation and relativistic corrections and logically simpler to include quantum electrodynamic (QED) corrections and higher order relativistic effects than the MCDF method. A recent development in extensive relativistic configuration interaction is also described.