# A comparison between quantum chemistry and quantum Monte Carlo techniques for the adsorption of water on the (001) LiH surface

## TL;DR

This study compares quantum chemistry and quantum Monte Carlo methods for calculating water adsorption on LiH surfaces, highlighting their reliability and potential to improve density functional approximations.

## Contribution

It provides a comprehensive benchmark of quantum chemical and Monte Carlo techniques for surface adsorption, assessing their accuracy and consistency.

## Key findings

- Quantum chemical methods are reliable for condensed phase calculations.
- Comparison shows differences and agreements among methods.
- Results suggest potential improvements for density functionals.

## Abstract

We present a comprehensive benchmark study of the adsorption energy of a single water molecule on the (001) LiH surface using periodic coupled cluster and quantum Monte Carlo theories. We benchmark and compare different implementations of quantum chemical wave function based theories in order to verify the reliability of the predicted adsorption energies and the employed approximations. Furthermore we compare the predicted adsorption energies to those obtained employing widely-used van der Waals density-functionals. Our findings show that quantum chemical approaches are becoming a robust and reliable tool for condensed phase electronic structure calculations, providing an additional tool that can also help in potentially improving currently available van der Waals density-functionals.