A critical assessment of two-body and three-body interactions in water

TL;DR

This paper critically evaluates two- and three-body water interactions using high-level CCSD(T) calculations, assesses various models, and introduces HBB2-pol, a new accurate interaction potential validated against experimental virial coefficients.

Contribution

It introduces HBB2-pol, a new water interaction model that accurately reproduces CCSD(T) results and experimental virial coefficients, improving simulation reliability.

Findings

HBB2-pol accurately maps CCSD(T) water interactions.

HBB2-pol matches experimental virial coefficients.

Force fields and DFT show varying accuracy.

Abstract

The microscopic behavior of water under different conditions and in different environments remains the subject of intense debate. A great number of the controversies arise due to the contradictory predictions obtained within different theoretical models. Relative to conclusions derived from force fields or density functional theory, there is comparably less room to dispute highly-correlated electronic structure calculations. Unfortunately, such ab initio calculations are severely limited by system size. In this study, a detailed analysis of the two- and three-body water interactions evaluated at the CCSD(T) level is carried out to quantitatively assess the accuracy of several force fields, density functional theory, and ab initio-based interaction potentials that are commonly used in molecular simulations. Based on this analysis, a new model, HBB2-pol, is introduced which is capable of accurately mapping CCSD(T) results for water dimers and trimers into an efficient analytical function. The accuracy of HBB2-pol is further established through comparison with the experimentally determined second and third virial coefficients.