Resonant Auger Decay in Benzene

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics
• Spectroscopy

Background:

• Resonant Auger decay involves core-level electron excitation followed by Auger decay.
• This process yields higher-energy Auger electrons than nonresonant decay.
• Understanding these spectra provides insights into electronic structure and molecular dynamics.

Purpose of the Study:

• To compute the resonant Auger spectrum of benzene using ab initio methods.
• To explain key features observed in experimental spectra.
• To evaluate the capabilities and limitations of theoretical approaches, specifically equation-of-motion coupled-cluster (EOM-CC) methods.

Main Methods:

• Ab initio calculations employing equation-of-motion coupled-cluster (EOM-CC) theory.
• Application of the Feshbach-Fano approach for participator decay.
• Investigation of EOM-CC singles and doubles (SD) approximation and the impact of triple excitations.

Main Results:

• The Feshbach-Fano approach with EOM-CC(SD) accurately describes participator decay in benzene.
• Spectator decay is more challenging to model due to doubly excited target states.
• Including triple excitations in the EOM-CC wave function is crucial for accurately describing spectator decay.

Conclusions:

• Resonant Auger decay in benzene serves as a stringent test for EOM-CC theory.
• Accurate theoretical treatment necessitates the inclusion of triple excitations, particularly for spectator decay.
• Noniterative triple corrections may be insufficient, highlighting the need for iterative inclusion of triple excitations.