Communication: Unambiguous comparison of many-electron wavefunctions through their overlaps

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Comparing many-electron wavefunctions from different theoretical models is crucial for understanding chemical phenomena.
• Existing methods like orbital visualization or comparing observables have limitations in capturing full wavefunction complexity.

Purpose of the Study:

• To introduce a robust and simple method for comparing many-electron wavefunctions.
• To analyze the impact of varying theoretical models, molecular orbitals, and basis sets on wavefunctions.
• To provide a tool for automatic monitoring of excited state ordering in calculations.

Main Methods:

• The study presents a method based on computing wavefunction overlaps.
• This approach processes many-electron wavefunctions in their full complexity.
• The method is demonstrated using multireference computations on selenoacrolein and an iridium complex.

Main Results:

• Wavefunction overlaps offer an unambiguous way to compare wavefunctions, overcoming limitations of simpler methods.
• The method effectively analyzes the influence of different theoretical parameters.
• It successfully monitors changes in excited state ordering for the tested systems.

Conclusions:

• Wavefunction overlap computation is a powerful and versatile tool for advanced quantum chemistry.
• It provides a more complete and less ambiguous analysis of theoretical models compared to traditional approaches.
• The method is particularly valuable for complex systems and excited state investigations.