Binding Energies from Diffusion Monte Carlo for the MB-pol H_2O and D_2O Dimer: A Comparison to Experimental Values

TL;DR

This paper uses Diffusion Monte Carlo to calculate the binding energies of water dimers and their isotopomers with high accuracy, validating the MB-pol potential against experimental data.

Contribution

It demonstrates the high accuracy of the MB-pol potential energy surface in predicting water dimer binding energies using DMC methods.

Findings

DMC binding energies agree with experimental values within 0.02 kcal/mol.

MB-pol potential provides highly accurate predictions for water dimer energies.

Results support MB-pol's reliability for simulating water clusters.

Abstract

The Diffusion Monte Carlo (DMC) method is applied to compute the ground state energies of the water monomer and dimer and their D 2 O isotopomers using MB-pol; the most recent and most accurate ab inito- based potential energy surface (PES). MB-pol has already demonstrated excellent agreement with high level electronic structure data, as well as agreement with some experimental, spectroscopic, and thermodynamic data. Here, the DMC binding energies of (H 2 O) 2 and (D 2 O) 2 agree with the corresponding values obtained from velocity map imaging within, respectively, 0.01 and 0.02 kcal/mol. This work adds two more valuable data points that highlight the accuracy of the MB-pol PES.