Calculating Off-Site Excitations in Symmetric Donor-Acceptor Systems via Time-Dependent Density Functional Theory...

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Off-site excitations involve charge transfer between spatially separated orbitals.
• Symmetrical systems can exhibit "hidden" charge-transfer excitations due to orbital degeneracy.
• Conventional density functionals often fail to accurately capture these hidden excitations.

Purpose of the Study:

• To investigate the accurate characterization of hidden charge-transfer excitations.
• To evaluate the performance of time-dependent density functional theory with range-separated hybrid functionals for these excitations.
• To apply this methodology to model systems and functionalized materials.

Main Methods:

• Utilizing time-dependent density functional theory (TD-DFT).
• Employing range-separated hybrid functionals, specifically the Baer-Neuhauser-Livshitz functional.
• Applying calculations to the ethene dimer model and dye-functionalized silsesquioxanes.

Main Results:

• The Baer-Neuhauser-Livshitz functional accurately characterizes hidden off-site excitation energies.
• Demonstrated accurate calculation of excitation energies in both model and complex systems.
• Highlighted the limitations of conventional density functionals for such excitations.

Conclusions:

• Range-separated hybrid functionals offer a robust approach for studying hidden charge-transfer excitations.
• This method advances the accurate computational prediction of electronic properties in weakly coupled systems.
• The findings are relevant for designing and understanding advanced materials.