Improving PCM in Protic Media: Markov State Models for TD-DFT Calculations

Area of Science:

• Computational Chemistry
• Spectroscopy
• Materials Science

Background:

• Accurately predicting optical properties of dyes in protic media is challenging.
• Standard polarizable continuum models (PCM) often fail to capture specific solute-solvent interactions.

Purpose of the Study:

• To introduce a novel computational workflow for predicting optical properties of dyes in protic solvents.
• To improve the accuracy and cost-effectiveness of modeling electronic excitations in complex systems.

Main Methods:

• Combining molecular dynamics (MD) simulations, time-lagged independent component analysis (TICA), and Markov State Models (MSM).
• Utilizing time-dependent density functional theory (TD-DFT) with explicit H-bonded solvent molecules.
• Developing an MSM(PCM)TD-DFT approach for analyzing system configurations.

Main Results:

• Identified key system configurations and macrostates relevant for electronic excitation modeling.
• Demonstrated that a few thermally accessible, non-optimized geometries can better represent experimental spectra than optimized structures.
• Validated the approach on compounds with strong charge-transfer character.

Conclusions:

• The MSM(PCM)TD-DFT workflow provides a promising and cost-effective method for understanding dye behavior in protic media.
• This approach enhances the predictive power for optical properties by accounting for crucial solute-solvent interactions.