On a simple way to calculate electronic resonances for polyatomic molecules

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Calculating electronic resonances in molecules is crucial for understanding their stability and reactivity.
• Existing methods can be computationally intensive or lack robustness.

Purpose of the Study:

• To present a simple, stable, and robust method for calculating low-lying shape electronic resonances of polyatomic molecules.
• To demonstrate the method's applicability using high-level correlation treatments.

Main Methods:

• The proposed method utilizes a perturbation potential and standard bound-state calculations in the real energy domain.
• It is based on analytical continuation in a coupling constant model, enhanced for stability.
• The approach is independent of the specific correlation treatment, allowing for methods like Coupled Clusters (CCSD-T).

Main Results:

• The method exhibits stable and robust behavior for higher-order extrapolation functions.
• It successfully determined the resonance position and width of the (2)Πu temporary negative ion state of diacetylene.
• The calculations were performed using the CCSD-T (Coupled Clusters with Singles, Doubles, and perturbative Triples) level of theory.

Conclusions:

• The presented method provides an accessible and reliable way to compute molecular electronic resonances.
• Its robustness and independence from correlation treatment make it widely applicable in quantum chemistry.
• This technique facilitates accurate characterization of temporary negative ion states in molecules.