A Graph-based Methodology for Modeling the Nucleation of Weak Electrolytes

在化学系化学理论、模型和计算方法计划的支持下，威斯康星大学麦迪逊分校的乔丹·R·施密特教授将开发新的方法来模拟晶体在溶液中的生长。晶体的成核和生长是一种普遍存在的现象，它是许多化学和生物过程的基础，从水冰的形成到通过生物矿化的骨骼生长。施密特和他的研究团队将开发和应用新的方法，允许通过计算机模拟对晶体生长的初始阶段进行原子细节检查，这可能会为更好地理解如何指导和控制重要晶体材料的生长打开大门。将特别强调对具有低溶解度的重要溶质的生长进行建模，例如新兴的纳米多孔材料，而现有的模拟方法是不足的。施密特教授还将通过参加密歇根大学麦迪逊化学机会(CHOPS)和通向博士学位课程的ACS桥梁，进一步努力扩大理论化学在这个项目和更广泛的科学界的参与。施密特团队还将专注于K-12推广活动，包括在当地中小学和威斯康星科学节上的化学现场演示。在这个项目中，威斯康星大学麦迪逊分校的施密特小组将开发和应用一种基于图论的方法，该方法针对晶体结构表现出定向键合的材料，无论是纯静电的，还是通过配位络合物的，因此可以被描述为连接单体的“图”。使用自举方法，生长核的自由能将通过一种植根于统计热力学的严格方法来计算。该方法消除了这种弱电解液成核所固有的长度和时间刻度限制(例如，质量传输、去溶)，这些限制目前排除了对弱电解液成核的原子模拟。在开发、验证和优化以进一步提高这种基于图形的方法的效率之后，该团队将探索在简单盐、弱电解液和纳米多孔材料(即金属-有机骨架)中的应用，这是一类重要的低溶解度材料，成核在材料合成和晶体工程中起着关键(往往也是有限的)作用。最终的代码/脚本将通过GitHub以开源形式发布，以使广大科学界能够将其应用到其他领域。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, Professor Jordan R. Schmidt of University of Wisconsin-Madison will develop new methods for simulating the growth of crystals in solution. The nucleation and growth of crystals is a ubiquitous phenomenon that underlies many chemical and biological processes, from the formation of water ice to the growth of bone via biomineralization. Schmidt and his research team will develop and apply new methods that allow the initial stages of crystal growth to be examined in atomistic detail via computer simulations, potentially opening the door to a better understanding for how to direct and control the growth of important crystalline materials. A special emphasis will be placed on modeling the growth of important solutes with low solubility, e.g., emerging nano-porous materials, where existing simulation methods are inadequate. Professor Schmidt will also conduct additional efforts to broaden participation in theoretical chemistry, both in this project and in the wider scientific community, via participation in the UW Madison Chemistry Opportunities (ChOPS) and ACS Bridge to the Doctorate programs. The Schmidt team will also focus on K-12 outreach activities, including live chemistry demonstrations, including those on crystal nucleation, at local elementary and middle schools and the Wisconsin Science Festival.In this project, the Schmidt group at U. Wisconsin-Madison will develop and apply a graph theory-based methodology that is tailored toward materials whose crystal structure exhibits directional bonding, whether purely electrostatic, or via coordination complexes, and thus can be described as a “graph” of connected monomers. Using a bootstrapping approach, the free energies of growing nuclei will be calculated via a rigorous approach rooted in statistical thermodynamics. The methodology eliminates the length- and timescale limitations inherent to the nucleation of such weak electrolytes (e.g. mass transport, desolvation) that currently preclude the atomistic simulation of weak electrolyte nucleation. Following development, validation and optimizations to further enhance the efficiency of this graph-based approach, the team will explore applications to simple salts, weak electrolytes, and nano-porous materials (i.e., metal-organic frameworks), an important class of low-solubility material where nucleation plays a key (and often limiting) role in materials synthesis and crystal engineering. The resulting codes/scripts will be released in open-source form via GitHub to enable applications to other domains by the scientific community at large.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.