Simulating X-ray photoelectron spectra with strong electron correlation using multireference algebraic diagrammatic...

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Computational Physics

Background:

• Simulating X-ray photoelectron spectra (XPS) of strongly correlated molecular systems presents significant computational challenges.
• Conventional multireference theories struggle with accurate calculations of excitations from inner-shell and core molecular orbitals.

Purpose of the Study:

• To develop a computationally efficient and accurate theoretical approach for XPS simulations of strongly correlated molecules.
• To overcome limitations of existing multireference theories for core-level spectroscopy.

Main Methods:

• Combining multireference algebraic diagrammatic construction theory (MR-ADC) with a core-valence separation (CVS) technique.
• The novel CVS-MR-ADC approach is applied to model systems with varying degrees of electronic correlation.

Main Results:

• CVS-MR-ADC methods achieve accuracy comparable to single-reference methods for weakly correlated systems.
• Demonstrated superior accuracy and reliability for strongly correlated systems like stretched N2, ozone, and benzyne diradicals.
• Highlighted the critical role of multireference effects in describing core-hole screening for XPS peak analysis.

Conclusions:

• The CVS-MR-ADC method offers a powerful and efficient tool for XPS simulations of complex molecular systems.
• This approach accurately captures essential multireference effects crucial for interpreting core-level spectra.
• The findings advance the theoretical understanding and simulation capabilities for electronic structure and spectroscopy.