From Potentials to Properties: Data-Driven Many-Body Simulations of Water and Aqueous Systems.

Water is one of the most extensively studied molecular systems, yet its behavior across different phases, interfaces, and chemical environments continues to challenge existing models. Over the past decade, the development of data-driven many-body potential energy functions (PEFs) within the many-body energy (MB-nrg) formalism has enabled simulations of water and aqueous systems with unprecedented predictive power. Rooted in the many-body expansion and rigorously derived from "gold standard" electronic structure data, these PEFs bridge quantum chemistry and statistical mechanics within a unified framework. In this article, we review how the MB-pol PEF for water and the MB-nrg PEFs for hydrated halide and alkali metal ions have reshaped our understanding of aqueous properties across the gas, liquid, and solid phases, offering detailed insights into hydrogen bonding, spectroscopy, isotope effects, and phase stability. By connecting length scales and timescales while maintaining quantum-mechanical accuracy, the data-driven many-body MB-nrg formalism provides a robust foundation for realistic molecular simulations and offers new opportunities for addressing long-standing questions in physical chemistry and beyond.