Many-Body Contributions in Water Nano-Clusters

TL;DR

This study demonstrates that considering only the first coordination shell in water nano-clusters suffices to accurately approximate their global energy minima, enabling more efficient many-body potential development.

Contribution

It shows that including the first coordination shell captures most of the many-body effects in water clusters, simplifying potential models.

Findings

First coordination shell accounts for within 5% of energy minimum.

Results consistent across three different polarizable models.

Proposes a strategy for efficient many-body potential development.

Abstract

Many-body interactions in water are known to be important but difficult to treat in atomistic models and often are included only as a correction. Polarizable models treat them explicitly, with long-range many-body potentials, within their classical approximation. However, their calculation is computationally expensive. Here, we evaluate how relevant the contributions to the many-body interaction associated with different coordination shells are. We calculate the global energy minimum, and the corresponding configuration, for nano-clusters of up to 20 water molecules. We find that including the first coordination shell, i.e., the five-body term of the central molecule, is enough to approximate within 5% the global energy minimum and its structure. We show that this result is valid for three different polarizable models, the Dang-Chang, the MB-pol, and the Kozack-Jordan potentials. This result suggests a strategy to develop many-body potentials for water that are reliable and, at the same time, computationally efficient.