Abstract
Fano-ADC-Stieltjes is an ab initio L2 method for the decay width calculations of metastable states of atoms and molecules. It relies on Fano-Feshbach theory of resonances to describe bound-like discrete and continuum states and on algebraic diagrammatic construction in intermediate states representation (ISR-ADC) to construct many-electron wave functions.
Correct renormalization of discretized continuum is achieved by Stieltjes imaging technique. Favorable numerical properties are fast convergence and size extensivity.
We assess this method as the most efficient one for studying non-radiative relaxation processes such as Auger effect or Interatomic Coulombic decay (ICD). In ICD, an inner-valence vacancy is filled by an outer-valence electron and the excess energy is transferred to a neighboring atom which is thus ionized.
We study new ICD mechanism called Superexchange blockade in NeHeNe trimer. The blockade effect originates in the destructive interference between different available interatomic decay pathways and is reflected in a sharp decrease in the respective decay width.
It occurs for geometries where the resonance state becomes nearly degenerate with another electronic bound state of the system, with which it interacts through so-called avoided crossing.