Semiempirical configuration interaction calculations for ru-centered dyes.

Area of Science:

• Computational chemistry
• Photochemistry
• Materials science

Background:

• Investigating transition-metal dyes often requires molecular structure optimization and UV/visible spectrum calculation.
• Density functional theory (DFT) and time-dependent DFT are standard but computationally intensive methods.
• Semiempirical methods offer faster screening but require careful parameterization for accuracy.

Purpose of the Study:

• To develop and validate a modified configuration interaction (CI) method based on the semiempirical PM6 Hamiltonian for calculating UV/visible absorption spectra.
• To improve the accuracy of computational predictions for ruthenium-centered complexes.
• To provide a more efficient computational tool for screening transition-metal dyes.

Main Methods:

• Modification of a configuration interaction (CI) method using a semiempirical PM6 Hamiltonian.
• Scaling of two-center, two-electron Coulomb integrals within the CI method.
• Validation against experimental absorption spectra and DFT calculations using a training set of 13 Ru-centered complexes.

Main Results:

• The modified PM6-based CI method demonstrates a significantly better agreement with experimental absorption spectra compared to the default CI method.
• The new method accurately blue-shifts metal-to-ligand charge-transfer (MLCT) peaks, aligning better with experimental and DFT results.
• The modification corrects a key deficiency of the unmodified semiempirical CI approach.

Conclusions:

• The modified PM6-based CI method provides a more accurate and efficient approach for calculating UV/visible absorption spectra of Ru-centered complexes.
• This enhanced method can accelerate the discovery and design of new transition-metal dyes.
• The study highlights the potential of parameterized semiempirical methods for photochemical property investigations.