Fano-Feshbach formalism applied to the calculation of autoionization widths through analytic continuation

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics
• Computational Chemistry

Background:

• Autoionization width is crucial for understanding resonance phenomena in atoms and molecules.
• Calculating this width often requires complex theoretical formalisms and computational resources.
• Existing methods may face challenges with accuracy or applicability across different systems.

Purpose of the Study:

• To propose a novel and efficient method for calculating autoionization width.
• To validate the proposed method using analytic continuation of Green's function.
• To demonstrate the method's applicability to both atomic and molecular systems.

Main Methods:

• Utilizing a discretized pseudo-spectrum obtained from multireference configuration interaction calculations.
• Employing analytic continuation of Green's function within the Fano-Feshbach formalism.
• Applying the method to helium, neon, hydrogen fluoride, and benzene.

Main Results:

• The proposed method successfully calculates the autoionization width from pseudo-spectra.
• Results obtained for atomic and molecular systems show good agreement with theoretical and experimental values.
• The method requires only a few states around the resonance for accurate analytic continuation.

Conclusions:

• The developed method provides a reliable way to compute autoionization widths.
• This approach offers an efficient alternative for studying resonance phenomena in various chemical systems.
• The findings contribute to advancing computational methods in quantum chemistry and atomic/molecular physics.