Ab-initio calculations of Many-Body effects in liquids: the electronic excitations of water

TL;DR

This paper uses ab-initio Many-Body Green's function methods to calculate the electronic excitations of liquid water, revealing significant many-body effects that align well with experimental spectra.

Contribution

It introduces a novel approach combining MD snapshots with Many-Body Green's function calculations to accurately model water's excited states.

Findings

Many-body effects significantly alter spectral features.

Calculated spectra agree well with experimental data.

Screening effects are relatively insensitive to configuration variations.

Abstract

We present ab-initio calculations of the excited state properties of liquid water in the framework of Many-Body Green's function formalism. Snapshots taken from molecular dynamics simulations are used as input geometries to calculate electronic and optical spectra, and the results are averaged over the different configurations. The optical absorption spectra with the inclusion of excitonic effects are calculated by solving the Bethe-Salpeter equation. These calculations are made possible by exploiting the insensitivity of screening effects to a particular configuration. The resulting spectra are strongly modified by many-body effects, both concerning peak energies and lineshapes, and are in good agreement with experiments.