Structure and Reactivity at the Mineral-Water Interface

矿泉水界面的结构和反应性

• 批准号: 1227215
• 负责人: Barry Bickmore
• 金额: $ 21.55万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1227215&HistoricalAwards=false
• 关键词: Structure; Reactivity; Mineral; Water; Interface

Technical Summary. Progress in low-temperature geochemistry will largely depend on our ability to characterize reaction mechanisms and energetics at the mineral-water interface. But these systems are usually so complex that it is difficult or impossible to obtain either precise experimental characterizations or accurate calculations of reaction energetics. We suggest that more rapid progress could be made if we better understood the relationship between molecular structure and reactivity at the interface. Our proposed research will address this problem by attempting to create a fairly comprehensive structure-energy model based on the bond-valence model (BVM), which is a standard tool in crystallography and inorganic chemistry. Model development will proceed via optimization of some novel potential energy terms based on BVM-based structural descriptors. We will optimize the model parameters on known crystal structures, and test it on calculated structures of simple aqueous systems, crystals, and interfaces, with the calculations performed at a high level of theory. Such a model would be unique, in that it would be based on only a few potential energy terms that very simply take into account complex, multi-body interactions. This would allow us to more profitably interpret structural information regarding interfaces gleaned from advanced experimental and computational studies of these systems, and it may also prove to be an excellent foundation for advanced force fields for use in further computational studies. To this end, we also propose to implement our model within a standard molecular modeling code.Broader Significance. Risk analysis and mitigation strategies for many environmental problems, including groundwater contamination and nuclear waste disposal, rely on computer models of processes that include reactions at mineral-water interfaces. And yet, these reactions are notoriously difficult to study. Our proposed research will make it easier for scientists to interpret results from experimental and advanced computational studies of these reactions, and may also prove useful for making the computational studies more accurate and broadly applicable.In fact, the results of our proposed work are likely to be applicable far beyond the discipline of low-temperature geochemistry, since we will be taking an empirical model of molecular geometry that is already a mainstay among a very broad community of scientists and developing it in a more comprehensive way. Furthermore, the research will be pursued in the context of an innovative mentoring environment already established at Brigham Young University (BYU) -the Interdisciplinary Mentoring Program in Analysis, Computation, and Theory (IMPACT). Students, both graduates and undergraduates, in this program are given intensive training in applied mathematics and computation, and assigned to work with faculty from various disciplines to solve problems or develop mathematical models of important processes. In the context of this project, they will also be given intensive training in basic mathematical crystallography, basic computational chemistry, and the BVM. Students will be recruited from both the Mathematics and Geological Sciences departments at BYU, with the aim of using this mentoring experience to develop human capital in the Earth Sciences. These disciplines deal with very complex systems that can usually be effectively simulated only on the basis of exceptionally complex numerical models, and both the public and governmental agencies are increasingly turning to the results of such models to make critical decisions. Yet, students in the Earth Sciences are typically not required to take many classes in mathematics, and often graduate without really understanding how the mathematics they were required to take can be applied to their discipline. IMPACT is designed to cut through differences in jargon and help participating students see how a simple toolbox of numerical techniques can be applied across many disciplines. This allows students to develop the ability to think fluently in this critically important language.

技术总结。 在低温地球化学的进展将在很大程度上取决于我们的能力，在矿物-水界面的反应机制和能量的特点。 但是这些体系通常非常复杂，很难或不可能获得精确的实验表征或反应能量学的精确计算。 我们认为，如果我们更好地了解分子结构和反应性之间的关系，在界面上，可以取得更快的进展。我们提出的研究将解决这个问题，试图建立一个相当全面的结构能量模型的基础上键价模型（BVM），这是一个标准的工具，在晶体学和无机化学。 模型开发将通过优化一些新的势能项的基础上，基于BVM的结构描述符。 我们将在已知的晶体结构上优化模型参数，并在简单的水溶液系统，晶体和界面的计算结构上进行测试，并在高理论水平上进行计算。 这样的模型将是独一无二的，因为它将仅基于几个势能项，非常简单地考虑到复杂的多体相互作用。这将使我们能够更有利地解释从这些系统的高级实验和计算研究中收集到的关于界面的结构信息，并且它也可能被证明是用于进一步计算研究的高级力场的良好基础。 为此，我们还建议在一个标准的分子建模代码中实现我们的模型。 许多环境问题的风险分析和缓解战略，包括地下水污染和核废料处置，依赖于计算机模型的过程，包括在矿物质-水界面的反应。 然而，这些反应是出了名的难以研究。 我们提出的研究将使科学家更容易解释这些反应的实验和高级计算研究的结果，也可能证明有助于使计算研究更准确和更广泛地适用。事实上，我们提出的工作的结果可能适用于远远超出低温地球化学学科，因为我们将采用分子几何学的经验模型，这已经是一个非常广泛的科学家社区的支柱，并以更全面的方式发展它。 此外，研究将在杨百翰大学（BYU）已经建立的创新指导环境的背景下进行-分析，计算和理论（IMPACT）的跨学科指导计划。 学生，无论是研究生和本科生，在这个程序中给予应用数学和计算密集的培训，并分配到工作与教师从不同学科解决问题或开发重要过程的数学模型。 在这个项目的背景下，他们还将在基础数学晶体学，基础计算化学和BVM方面进行强化培训。 学生将从杨百翰大学的数学和地质科学系招募，目的是利用这种指导经验来开发地球科学的人力资本。 这些学科处理非常复杂的系统，通常只能在非常复杂的数值模型的基础上进行有效的模拟，公众和政府机构越来越多地转向这种模型的结果来做出关键决策。 然而，学生在地球科学通常不需要采取许多类的数学，往往毕业没有真正了解如何数学，他们需要采取可以应用到他们的纪律。 IMPACT旨在消除术语的差异，并帮助参与的学生了解如何在许多学科中应用一个简单的数值技术工具箱。 这使学生能够培养用这门至关重要的语言流利思考的能力。