Electronic structure theory of exotic atoms and molecules

Experiments on heavy and radioactive atoms and molecules are extremely challenging due to the short lifetimes and the low quantities of these species. Specially developed experimental techniques are thus needed to carry out such studies, but no less important for their success is strong and reliable theoretical support. For example, predictions of spectroscopic properties are necessary for planning the measurements and the possible laser cooling or trapping schemes. Furthermore, theoretical input is crucial for interpreting these measurements and provides the link between the experimental spectroscopy and the nuclear and particle physics. Knowledge of various electronic coupling factors is needed to extract the properties of interest, such as the electron  EDM, the anapole moments, or any other parity violating property. These coupling factors cannot be measured, and are provided from electronic structure calculations.

In order to be reliable, such calculations must include both relativistic effects and electron correlation on the highest possible level. This is especially important for heavy systems, where relativity has a major effect on the electronic structure and properties and the large number of electrons requires state-of-the-art treatment of correlation. 

Relativistic coupled cluster is considered one of the most powerful methods for accurate investigations of heavy many-electron systems. This approach can be used to obtain atomic and molecular properties, including the various coupling parameters needed for the interpretation of precision experiments that search for signatures of physics beyond the Standard Model. It has been shown to be extremely reliable and to have very strong predictive power.

A brief introduction to the relativistic coupled cluster method will be provided in my talk. I will, however, focus on the recent successful applications of this approach to heavy molecules, in particular in connection to recent and planned experiments.