Excitonic Approach for Nonadiabatic Dynamics: Extending Beyond the Frenkel Exciton Model

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Simulating multichromophoric systems requires accurate models for electronic dynamics.
• Existing methods may not fully capture complex phenomena like charge transfer states.

Purpose of the Study:

• To introduce and validate an extended Frenkel exciton model (EFEM) for multichromophoric systems.
• To incorporate interchromophore charge transfer states and simultaneous double excitations into the model.

Main Methods:

• Formulation of an extended Frenkel exciton model (EFEM).
• Utilizing semiempirical floating occupation molecular orbitals-configuration interaction (FOMO-CI) for electronic structure.
• Employing nonadiabatic molecular dynamics with a surface hopping approach.

Main Results:

• The EFEM was successfully implemented for simulating multichromophoric system dynamics.
• Simulations of singlet fission in a ThBF trimer validated the EFEM's accuracy.
• EFEM results were compared against the standard "supermolecule" approach.

Conclusions:

• The EFEM provides a robust framework for studying exciton dynamics in complex molecular aggregates.
• The model accurately describes processes like singlet fission, crucial for organic electronics.
• EFEM offers a valuable computational tool for designing novel photoactive materials.