Advanced Relativistic Energy Approach in Spectroscopy of Autoionization States of Multielectron Atomic Systems

Abstract

We present the generalized energy approach to relativistic calculation of the autoionization decay (resonances) energies and probabilities (widths) in the neutral multielectron atomic systems and multicharged ions. The approach is based on the Gell-Mann and Low S-matrix formalism and the relativistic many-body perturbation theory (PT) with using the optimized one-quasiparticle representation and an accurate account of the relativistic and correlation. In relativistic case the Gell-Mann and Low formula expresses an energy shift \(\Delta {\rm E}\) through the electrodynamical scattering matrix including the interaction with as the laser field as the photon vacuum field. The last case is corresponding to definition of the radiative and autoionization decays probabilities for atomic systems. As illustration, the results of relativistic calculation of the autoionization states energies and widths are presented for a number of atoms (helium, barium) and discussed from viewpoint of the correct accounting for the relativistic and exchange-correlation effects.