A Polarizable Water Potential Derived from a Model Electron Density

TL;DR

This paper introduces HIPPO, a new polarizable water potential derived from a model electron density, enabling efficient large-scale molecular dynamics simulations with improved accuracy across various water phases.

Contribution

The paper presents a novel, physics-based water potential derived from a model electron density, systematically parameterized and validated against ab initio energy components and experimental data.

Findings

Accurately reproduces properties of water clusters, liquid water, and ice.

Provides a balanced description of water's structure, dynamics, and thermodynamics.

Achieves accuracy comparable or superior to existing polarizable force fields.

Abstract

A new empirical potential for efficient, large scale molecular dynamics simulation of water is presented. The HIPPO (Hydrogen-like Intermolecular Polarizable POtential) force field is based upon the model electron density of a hydrogen-like atom. This framework is used to derive and parameterize individual terms describing charge penetration damped permanent electrostatics, damped polarization, charge transfer, anisotropic Pauli repulsion, and damped dispersion interactions. Initial parameter values were fit to Symmetry Adapted Perturbation Theory (SAPT) energy components for ten water dimer configurations, as well as the radial and angular dependence of the canonical dimer. The SAPT-based parameters were then systematically refined to extend the treatment to water bulk phases. The final HIPPO water model provides a balanced representation of a wide variety of properties of gas phase clusters, liquid water and ice polymorphs, across a range of temperatures and pressures. This water potential yields a rationalization of water structure, dynamics and thermodynamics explicitly correlated with an ab initio energy decomposition, while providing a level of accuracy comparable or superior to previous polarizable atomic multipole force fields. The HIPPO water model serves as a cornerstone around which similarly detailed physics-based models can be developed for additional molecular species.