Modeling Electronic Excited States of Molecules in Solution

TL;DR

This paper reviews methods for modeling the excited states of molecules in solution, emphasizing explicit solvent interactions, configuration sampling, and spectral simulation techniques to improve understanding of solution-phase properties.

Contribution

It introduces practical guidelines for simulating excited states with explicit solvent, including a novel approach combining ensemble excitation energies with vibronic spectra.

Findings

Improved absorption spectrum simulations for molecules in solution.

Effective sampling strategies for solute-solvent configurations.

Validation of combined spectral simulation methods.

Abstract

The presence of solvent tunes many properties of a molecule, such as its ground and excited state geometry, dipole moment, excitation energy, and absorption spectrum. Because the energy of the system will vary depending on the solvent configuration, explicit solute-solvent interactions are key to understanding solution-phase reactivity and spectroscopy, simulating accurate inhomogeneous broadening, and predicting absorption spectra. In this tutorial review, we give an overview of factors to consider when modeling excited states of molecules interacting with explicit solvent. We provide practical guidelines for sampling solute-solvent configurations, choosing a solvent model, performing the excited state electronic structure calculations, and computing spectral lineshapes. We also present our recent results combining the vertical excitation energies computed from an ensemble of solute-solvent configurations with the vibronic spectra obtained from a small number of frozen solvent configurations, resulting in improved simulation of absorption spectra for molecules in solution.