De-perturbative corrections for charge-stabilized double ionization potential equation-of-motion coupled-cluster...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• The double ionization potential equation-of-motion (EOM-DIP) method is crucial for studying electron detachment processes.
• Unstable dianion references in EOM-DIP calculations necessitate charge stabilization, which can introduce energy perturbations.
• Accurate calculation of excitation energies is vital for understanding molecular properties.

Purpose of the Study:

• To develop and validate methods for removing energy perturbations caused by charge stabilization in EOM-DIP calculations.
• To benchmark the accuracy of corrected EOM-DIP results against established computational methods.
• To improve the reliability of EOM-DIP for systems with autoionizing dianion references.

Main Methods:

• Implementation of two distinct approaches to correct for stabilization potential-induced energy perturbations.
• Benchmarking calculations of excitation energies for selected diradical systems.
• Comparison of corrected EOM-DIP results with a high-level coupled-cluster method.

Main Results:

• The proposed core correction method effectively removes the undesirable energy perturbation from charge stabilization.
• Corrected EOM-DIP calculations yield excitation energies with small errors (0.0-0.3 eV) compared to coupled-cluster results.
• The core correction approach demonstrates robustness and reliability for EOM-DIP applications.

Conclusions:

• Charge stabilization can be reliably employed in EOM-DIP calculations with the developed core correction technique.
• The core correction method significantly enhances the accuracy of EOM-DIP for systems involving unstable dianion references.
• This work provides a more accurate and robust computational tool for studying electronic excitations in challenging molecular systems.