# Multimodel Approach to the Optical Properties of Molecular Dyes in Solution

## TL;DR

This paper presents a multimodel simulation approach combining explicit and implicit solvation models to accurately predict the optical absorption spectra of molecular dyes in solution, validated against experimental data.

## Contribution

The study introduces a novel multimodel method that efficiently combines explicit and implicit solvation effects for optical property simulations.

## Key findings

- Time-averaged spectra from multimodel and explicit simulations are highly similar.
- The multimodel approach significantly reduces computational resources.
- Predicted spectra agree well with experimental measurements.

## Abstract

We introduce a multimodel approach to the simulation of the optical properties of molecular dyes in solution, whereby the effects of thermal fluctuations and of dielectric screening on the absorption spectra are accounted for by explicit and implicit solvation models, respectively. Thermal effects are treated by averaging the spectra of molecular configurations generated by an ab initio molecular-dynamics simulation where solvent molecules are treated explicitly. Dielectric effects are then dealt with implicitly by computing the spectra upon removal of the solvent molecules and their replacement with an effective medium, in the spirit of a continuum solvation model. Our multimodel approach is validated by comparing its predictions with those of a fully explicit-solvation simulation for cyanidin-3-glucoside (cyanin) chromophore in water. While multimodel and fully explicit-solvent spectra may differ considerably for individual configurations along the trajectory, their time averages are remarkably similar, thus providing a solid benchmark of the former and allowing us to save considerably on the computer resources needed to predict accurate absorption spectra. The power of the proposed methodology is finally demonstrated by the excellent agreement between its predictions and the absorption spectra of cyanin measured at strong and intermediate acidity conditions.