Applications of many-body perturbation theory to actinide atoms

4^th International Conference on Atomic and Nuclear Physics

October 26-27, 2018 | Boston, USA

Igor M Savukov

Los Alamos National Laboratory, USA

Scientific Tracks Abstracts: J Astrophys Aerospace Technol

Abstract :

There are three main challenges for accurate applications of atomic theory to calculations of energy levels and other properties of Actinide atoms. First, the valence-valence interaction is strong and requires a large configuration space to account for this interaction. Various methods have implemented small configuration space and cannot account for the interaction with highly excited states and continuum. Second, the valence-core interaction is also strong and second-order MBPT, which is usually implemented in the configuration-interaction (CI) many-body perturbation theory (MBPT) method, is not adequate. Finally, the relativistic effects are significant breaking the LS-coupling scheme and making the transition amplitudes sensitive to these corrections. The approach of relativistic CI-MBPT is quite promising. It proved to give quite accurate results in light atoms, where the valence-core interaction can be described well in the second order and relativistic effects can be accounted for by employing Dirac-Fock basis and adding dominant Breit interactions. However, ab initio CI-MBPT completely fails in actinides. Still, significant improvement in accuracy can be achieved by introducing adjustable parameters. In particular, seven such parameters can be used to correct the single-valence energy, while additional two parameters can be used to improve the Coulomb screening. With 9-parameter CI-MBPT approach it is possible to reproduce energy levels in as complex an atom as U I. In this talk, I will show examples of CI-MBPT calculations with adjustable parameters for complex atoms. The work is in progress and some future directions will be also discussed.

Biography :

Igor M Savukov has completed his PhD in 2002 at the University of Notre Dame, in the USA and in 2006 his postdoctoral studies at Princeton University. Currently, he is an R&D Scientist at Los Alamos National Laboratory. He has published 80 papers in reputed journals, h index 22 and has been working over 20 years in the field of atomic structure calculations especially in the field of relativistic many-body theory.

E-mail: isavukov@lanl.gov