An excited state paired interacting orbital method

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Spectroscopy

Background:

• Analyzing molecular excited states is crucial for understanding optical processes.
• Existing methods like Natural Transition Orbitals (NTO) and Paired Interacting Orbitals (PIO) offer partial insights.
• A need exists for a unified method to analyze complex molecular excitations.

Purpose of the Study:

• To introduce a new computational method, Excited State Paired Interacting Orbital (EPIO), for analyzing molecular excited states.
• To combine the strengths of PIO and NTO methods for a comprehensive analysis.
• To provide clear visualization and understanding of electronic transitions in composite systems.

Main Methods:

• The EPIO method is developed by integrating concepts from Paired Interacting Orbitals (PIO) and Natural Transition Orbitals (NTO).
• It utilizes fragmented molecular orbitals (MOs) to construct EPIOs.
• Excited state characteristics like charge transfer and local excitations are analyzed using EPIOs and their generation probabilities.

Main Results:

• The EPIO method successfully represents electronic transitions in composite molecular systems using a limited number of EPIOs.
• It provides clear information on the composition of molecular orbitals involved in excitation processes.
• The method allows for detailed analysis of excited state characters, including charge transfer and local excitations.

Conclusions:

• The EPIO method offers a powerful tool for analyzing and visualizing molecular excited states.
• It enhances the understanding of electronic transitions and their underlying molecular orbital compositions.
• This method is valuable for studying optical processes and other molecular excitation phenomena.