Exploring electronic resonances in pyridine: Insights from orbital stabilization techniques.

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Molecular Physics

Background:

• Electron attachment to molecules like pyridine creates temporary electronic resonances.
• These resonances are metastable states that can decay via electronic or nuclear pathways.
• Understanding these resonances is crucial for predicting molecular behavior and reactivity.

Purpose of the Study:

• To calculate the positions and widths of electronic resonances in pyridine below 10 eV.
• To identify and characterize previously unreported electronic resonances in pyridine.
• To elucidate the nature and decay channels of these resonances using theoretical methods.

Main Methods:

• Utilized orbital stabilization techniques.
• Employed bound electronic structure methods, including equation of motion coupled cluster and multi-reference methods.
• Applied multi-reference perturbation theory for accurate resonance characterization.

Main Results:

• Identified eight electronic resonances in pyridine (four 2B1 and four 2A2).
• Reported one novel 2B1 resonance and two previously undocumented 2A2 resonances.
• Classified resonances as one-particle shape, mixed, or core-excited, with lower energy ones being shape resonances.
• Multi-reference perturbation theory proved most effective for describing mixed-character resonances.

Conclusions:

• The study provides a comprehensive theoretical characterization of pyridine's electronic resonances.
• New resonances were discovered, expanding the known spectral features of pyridine.
• Dyson orbitals were calculated to offer insights into the decay mechanisms of these electronic states.