Water on hexagonal boron nitride from diffusion Monte Carlo

TL;DR

This study uses quantum Monte Carlo methods to accurately estimate water molecule interaction energy with hexagonal boron nitride, revealing significant deviations of common DFT functionals from these results.

Contribution

First quantum Monte Carlo calculation of water adsorption energy on hexagonal boron nitride, providing benchmark data for future computational studies.

Findings

Water monomer interaction energy is -84 +/- 5 meV.

Most DFT functionals significantly deviate from QMC results.

DFT better reproduces energy differences between adsorption sites.

Abstract

Despite a recent flurry of experimental and simulation studies, an accurate estimate of the interaction strength of water molecules with hexagonal boron nitride is lacking. Here we report quantum Monte Carlo results for the adsorption of a water monomer on a periodic hexagonal boron nitride sheet, which yield a water monomer interaction energy of -84 +/- 5 meV. We use the results to evaluate the performance of several widely used density functional theory (DFT) exchange correlation functionals, and find that they all deviate substantially. Differences in interaction energies between different adsorption sites are however better reproduced by DFT.