Data-Driven Many-Body Models for Molecular Simulations of Ions in Water: From Ionic Clusters to Concentrated Electrolyte Solutions

加州大学圣地亚哥分校的Francesco Paesani博士获得了化学系化学理论、模型和计算方法项目的奖项。对不同条件下水环境中离子的结构、热力学、动力学和光谱性质进行定量、分子水平表征是理解几个基本过程的关键，包括大气中离子-分子反应和离子诱导成核、溶液中的酸碱反应、生物通道中的离子传输以及气/液和固/液界面的多相过程。对水合离子在不同相和不同环境下的行为进行统一描述尤其具有挑战性，需要对离子-离子、离子-水和水-水相互作用相关的竞争性焓和熵效应进行定量评估，这些相互作用由核量子效应进一步调节。通过将数据驱动的多体势能函数与经典分子动力学和量子分子动力学相结合，Paesani将把他的多体分子动力学（MB-MD）方法扩展到水中离子的建模，从气相簇到体溶液。MB-MD方法为水系统的分子模拟提供了准确而高效的理论/计算框架，具有高精度和预测能力。在这个研究项目中，Paesani的目标是从单个多体贡献的角度对小气相团簇到整体溶液的单离子水化结构和热力学进行微观理解，确定单离子水化自由能和离子-离子结合自由能，并根据基本离子-水和水-水多体效应对其进行分解。表征电解质溶液中水的氢键结构和动力学，作为离子浓度和组成、离子-离子、离子-水和水-水的解缠贡献的函数。作为拟议研究的一部分而开发的理论/计算方法将对从化学到材料科学和生物学的广泛用户群体产生广泛影响，并将涉及对高中，本科生和研究生的培训和教育，他们将获得理论，计算和物理化学的坚实基础。拟议项目的跨学科性质将为学生提供在不同学科界面工作的机会，这将为他们广泛的职业生涯做好准备。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Francesco Paesani of the University of California-San Diego is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry. A quantitative, molecular-level characterization of the structural, thermodynamic, dynamical, and spectroscopic properties of ions in aqueous environments under different conditions is key to understanding several fundamental processes, including ion-molecule reactions and ion-induced nucleation in the atmosphere, acid-base reactions in solution, ion transport in biological channels, and multiphase processes at air/liquid and solid/liquid interfaces. A unified picture of the behavior of hydrated ions across different phases and in different environments is particularly challenging, requiring a quantitative assessment of competing enthalpic and entropic effects associated with the interplay between ion–ion, ion–water, and water–water interactions, which are further modulated by nuclear quantum effects. By combining data-driven many-body potential energy functions derived entirely from high-level ab initio reference data with both classical and quantum molecular dynamics, Paesani will extend his many-body molecular dynamics (MB-MD) methodology to the modeling of ions in water, from gas-phase clusters to bulk solutions. The MB-MD methodology provides an accurate, yet efficient, theoretical/computational framework for molecular simulations of aqueous systems with high accuracy and predictive power. In this research project Paesani aims to develop a microscopic understanding of single-ion hydration structure and thermodynamics from small gas-phase clusters to bulk solutions in terms of individual many-body contributions, determine single-ion hydration free energies and ion–ion association free energies and decompose them in terms of elementary ion–water and water–water many-body effects, and characterize water hydrogen-bond structure and dynamics in electrolyte solutions as a function of ion concentration and composition, disentangling ion–ion, ion–water and water–water contributions. The theoretical/ computational methodology developed as part of the proposed research will have broad impact on a wide range of user communities from chemistry to materials science and biology, and will involve the training and education of high school, undergraduate and graduate students who will acquire a solid foundation in theoretical, computational, and physical chemistry. The interdisciplinary nature of the proposed project will provide the students with the opportunity to work at the interface of different disciplines which will prepare them for a wide range of careers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.