# Quantum dynamics and spectroscopy of ab initio liquid water: the interplay of nuclear and electronic quantum effects

## TL;DR

This paper combines advanced simulation methods to accurately model the quantum effects of nuclei and electrons in liquid water, providing detailed insights into its structure, dynamics, and spectroscopy.

## Contribution

It introduces a computational approach that efficiently captures nuclear and electronic quantum effects in liquid water using path integral simulations with on-the-fly density functional theory evaluations.

## Key findings

- Accurate IR and Raman spectra of liquid water obtained
- Lower-level density functionals fail for quantum-treated nuclei
- New insights into the limitations of existing simulation methods

## Abstract

Understanding the reactivity and spectroscopy of aqueous solutions at the atomistic level is crucial for the elucidation and design of chemical processes. However, the simulation of these systems requires addressing the formidable challenges of treating the quantum nature of both the electrons and nuclei. Exploiting our recently developed methods that provide acceleration by up to two orders of magnitude, we combine path integral simulations with on-the-fly evaluation of the electronic structure at the hybrid density functional theory level to capture the interplay between nuclear quantum effects and the electronic surface. Here we show that this combination provides accurate structure and dynamics, including the full infra-red and Raman spectra of liquid water. This allows us to demonstrate and explain the failings of lower-level density functionals for dynamics and vibrational spectroscopy when the nuclei are treated quantum mechanically. These insights thus provide a foundation for the reliable investigation of spectroscopy and reactivity in aqueous environments.