Interstate vibronic coupling constants between electronic excited states for complex molecules

Area of Science:

• Computational Chemistry
• Quantum Dynamics
• Molecular Spectroscopy

Background:

• Accurate calculation of vibronic coupling constants is crucial for simulating quantum dynamics in excited molecular states.
• Current methods often rely solely on excited-state energies, limiting their applicability.
• Complex molecular systems with closely lying and interacting electronic states pose significant challenges.

Purpose of the Study:

• To develop and present a novel protocol for determining interstate vibronic coupling constants.
• To utilize time-dependent density functional theory (TD-DFT) and overlap integrals for this purpose.
• To demonstrate the method's utility for complex systems, including those with multiple interacting electronic states.

Main Methods:

• A new protocol is introduced to calculate vibronic coupling constants.
• The method employs overlap integrals between excited-state adiabatic auxiliary wavefunctions.
• Time-dependent density functional theory (TD-DFT) is utilized at this level.

Main Results:

• The protocol provides access to interstate vibronic coupling constants.
• The method is shown to be advantageous for systems with closely interacting electronic states.
• The protocol was successfully applied to prototype rhenium carbonyl complexes.

Conclusions:

• The developed protocol offers a robust method for obtaining vibronic coupling constants.
• This approach has significant potential for future studies of complex molecular systems.
• The method is particularly valuable for non-adiabatic quantum dynamics simulations involving spin-orbit coupling.