Relativistic decay widths of autoionization processes: The relativistic FanoADC-Stieltjes method

Abstract

Electronic decay processes of ionized systems are, for example, the Auger decay or the Interatomic/ Intermolecular Coulombic Decay. In both processes, an energetically low lying vacancy is filled by an electron of an energetically higher lying orbital and a secondary electron is instantaneously emitted to the continuum. Whether or not such a process occurs depends both on the energetic accessibility and the corresponding lifetime compared to the lifetime of competing decay mechanisms. We present a realization of the non-relativistically established FanoADC-Stieltjes method for the description of autoionization decay widths including relativistic effects. This procedure, being based on the Algebraic Diagrammatic Construction (ADC), was adapted to the relativistic framework and implemented into the relativistic quantum chemistry program package Dirac. It is, in contrast to other existing relativistic atomic codes, not limited to the description of autoionization lifetimes in spherically symmetric systems, but is instead also applicable to molecules and clusters. We employ this method to the Auger processes following the Kr3d(-1), Xe4d(-1), and Rn5d(-1) ionization. Based on the results, we show a pronounced influence of mainly scalar-relativistic effects on the decay widths of autoionization processes.

Using ICD for structural analysis of clusters: a case study on NeAr clusters

“…The distance dependence of the NeAr dimer decay width was calculated nonrelativistically for a number of points covering the distances that occur in the cluster. We have used the Fano-Stieltjes procedure implemented in DIRAC [45,46] with an aug-cc-pV6Z basis set on both atoms. Five additional basis functions each of s, p and d orbitals of the KBJ type [47], were introduced residing at the geometric center of the dimer.…”

Non-nearest neighbour ICD in clusters

“…By these means calculated discrete energies and corresponding transitions moments are then used to construct a continuous function, which is evaluated at the resonance energy approximated by the single ionization potential corresponding to the initial state E in . For a more detailed description of the method and comparison to other approaches see [39,40] and references therein.…”

Inner-shell photoionization and core-hole decay of Xe and XeF2

“…Theoretical treatments of inner-shell photoionization and core-hole decays in atoms and molecules have been actively studied in the literature. [30][31][32][33][34][35][36][37][38][39] Both nonrelativistic [30][31][32][33][34][35][36][37][38] and relativistic 39 Hamiltonians have been used together with a variety of quantum-chemical methods, ranging from the configuration interaction singles method to highorder Green's function techniques. The limitation of standard Gaussian functions in describing the regions outside the molecule, which is relevant to the dynamics of photoionization and core-hole decays, has been noted and discussed.…”