A Transferable H2O Interaction Potential Based on a Single Center Multipole Expansion: SCME

TL;DR

This paper introduces a new water interaction potential called SCME that uses a single-center multipole expansion for electrostatics, achieving high accuracy and transferability across different phases of water.

Contribution

The paper presents a novel single-center multipole expansion approach for water interactions, improving transferability and computational efficiency compared to traditional point charge models.

Findings

Accurately reproduces ab initio water interactions up to hexadecapole.

Simulates liquid water with results that agree well with experimental data.

Offers a fast evaluation method suitable for condensed phase simulations.

Abstract

A transferable potential energy function for describing the interaction between water molecules is presented. The electrostatic interaction is described rigorously using a multipole expansion. Only one expansion center is used per molecule to avoid the introduction of monopoles. This single center approach turns out to converge and give close agreement with ab initio calculations when carried out up to and including the hexadecapole. Both dipole and quadrupole polarizability is included. All parameters in the electrostatic interaction as well as the dispersion interaction are taken from ab initio calculations or experimental measurements of a single water molecule. The repulsive part of the interaction is parametrized to fit ab initio calculations of small water clusters and experimental measurements of ice Ih. The parametrized potential function was then used to simulate liquid water and the results agree well with experiment, even better than simulations using some of the point charge potentials fitted to liquid water. The evaluation of the new interaction potential for condensed phases is fast because point charges are not present and the interaction can, to a good approximation, be truncated at a finite range.