Diabatization based on the dipole and quadrupole: the DQ method.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Transforming adiabatic electronic states to diabatic states is crucial for understanding molecular dynamics and reaction mechanisms.
• Existing diabatization methods, often relying solely on dipole moments, have limitations in scope and applicability.
• A more versatile and convenient diabatization scheme is needed for broader applications in computational chemistry.

Purpose of the Study:

• To present a novel diabatization scheme, the DQ scheme, utilizing both dipole and quadrupole moments.
• To demonstrate the broader applicability of the DQ scheme beyond electron transfer reactions and its compatibility with various electronic structure methods.
• To showcase the convenience of the DQ scheme, particularly its independence from orbital transformations.

Main Methods:

• The DQ scheme employs dipole and quadrupole moments to calculate transformation coefficients for adiabatic-to-diabatic state conversion.
• The method is designed to be independent of specific electronic structure packages and molecular symmetry.
• Prototype applications were performed on LiH and phenol molecules.

Main Results:

• The DQ scheme successfully transforms adiabatic electronic states to diabatic states.
• Results obtained using the DQ scheme were compared with those from the established fourfold-way diabatization scheme for LiH and phenol.
• The DQ scheme demonstrated broader applicability and ease of use compared to dipole-only methods.

Conclusions:

• The DQ scheme provides a robust and versatile method for diabatization.
• Its reliance on dipole and quadrupole moments makes it applicable to a wider range of chemical systems and theoretical studies.
• The DQ scheme represents a significant advancement in computational chemistry tools for analyzing molecular electronic properties.