Electronic energy transfer studied by many-body Green's function theory.

Area of Science:

• Quantum chemistry
• Condensed matter physics
• Materials science

Background:

• Accurate prediction of excitation energy transfer (EET) is crucial for designing advanced materials.
• Traditional models often struggle with complex electronic interactions and condensed systems.

Purpose of the Study:

• To develop a robust theoretical framework for calculating EET coupling in both isolated and condensed systems.
• To investigate the role of electronic structure and system dimensionality on EET dynamics.

Main Methods:

• Combining many-body Green's function theory with Förster-Dexter theory.
• Utilizing accurate exciton wave functions from the Bethe-Salpeter equation.
• Employing the GW method for evaluating exchange-correlation effects in Dexter coupling.

Main Results:

• The approach accurately estimates EET coupling, validated against high-level quantum chemistry methods.
• Demonstrated applicability to periodic systems, specifically single-walled carbon nanotubes.
• Identified dark states as key players in nanotube-nanotube EET.
• Observed a rapid, distance-dependent EET rate (∼D^-12) between nanotubes, exceeding Förster model predictions.

Conclusions:

• The combined Green's function and Förster-Dexter theory provides a powerful tool for EET studies.
• Chirality and excitation type significantly influence EET in carbon nanotubes.
• The rapid decay of EET with distance highlights the importance of short-range interactions.