The Valence Multipole Model: Linking Structure and Reactivity

价多极模型：连接结构和反应性

• 批准号: 1424682
• 负责人: Barry Bickmore
• 金额: $ 43.38万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1424682&HistoricalAwards=false
• 关键词: Valence; Multipole; Model; Linking; Structure

Broader implications.Understanding chemical processes (what happens to molecules and atoms) on mineral and other solid surfaces is a critical part of the science underlying how minerals behave throughout nature. The science of such surfaces also has implications for industrially important processes involving solid surfaces, such as the catalysis used for plastics manufacturing. Scientists have found that in order to understand what happens on surfaces at the molecular scale, computational modeling of these processes is absolutely essential. This work focuses on advancing modeling of mineral surfaces, which is important for both geochemistry and chemistry. Currently, the theories and models used to simulate interactions between atoms and molecules exhibit a large range in both the quality of results and the kinds of problems that can be addressed. There is a great need for models that are mathematically simple enough to be applied to large systems of atoms, but that are capable of greater accuracy and transferability. The research team will work on creating such a model by expanding a simple bonding model commonly used by crystallographers, the Bond-Valence Model, in a manner that is easily applied to atomistic simulations. An additional component of this award entails building a future US STEM workforce that is capable not only in geoscience, but also in computer programming, modeling, and data analysis. In geoscience (as well as all fields of STEM), both in industry and academia, the ability to comfortably use computing is growing in its importance. Traditionally, geoscience degree programs do not require students to acquire significant computer programming and data analysis skills. This project will require undergraduate researchers to do data mining, exploratory data analysis, and optimization, using the MATLAB scientific programming environment. Training in these skills will be provided to the students by the principal investigator.This project has implications for science beyond geochemistry, and, as such, is being jointly funded by the Environmental Chemical Sciences program (NSF Division of Chemistry) and the cross-disciplinary NSF Computational and Data-Enabled Science and Engineering program.Technical description.In this project, principal investigator Barry Bickmore and his group will continue work to create a simplified chemical bonding model, based on the bond-valence model (BVM), that can be easily transferred to a molecular mechanics framework for atomistic simulations. The potential energy terms in this model are primarily based on multipole (monopole, dipole, and quadrupole) expansions of bond valences about each atom. These terms tend to be surprisingly predictable, and describe all major aspects of molecular structure, including distortions due to electronic structure effects (lone-pair and Jahn-Teller). They are also intrinsically multi-body terms that describe aspects of the total bonding environment about each atom, rather than focusing on individual atom pairs. This allows for very complex interactions to be modeled using a small number of parameters. The present work focuses on developing the bonding model to predict ideal values of the BVM-based structural descriptors, as well as energy cost functions for deviations from the ideal values. In addition, we are developing some preliminary molecular mechanics force fields to further test the concept. A number of undergraduate researchers will be involved in the project, and will learn computer programming, data analysis, and optimization techniques.

了解矿物和其他固体表面的化学过程（分子和原子发生了什么）是自然界中矿物行为的科学基础的关键部分。这种表面的科学也对涉及固体表面的工业重要过程有影响，例如用于塑料制造的催化剂。 科学家们发现，为了了解分子尺度上表面上发生的事情，对这些过程进行计算建模是绝对必要的。 这项工作的重点是推进矿物表面的建模，这对地球化学和化学都很重要。 目前，用于模拟原子和分子之间相互作用的理论和模型在结果的质量和可以解决的问题的种类方面都表现出很大的范围。 有一个很大的需要模型，数学上足够简单，适用于大型系统的原子，但能够更高的精度和可移植性。 研究团队将通过以易于应用于原子模拟的方式扩展晶体学家常用的简单键合模型（键价模型）来创建这样的模型。该奖项的另一个组成部分是建立一个未来的美国STEM劳动力，不仅在地球科学，而且在计算机编程，建模和数据分析能力。 在地球科学（以及STEM的所有领域），无论是在工业界还是学术界，舒适地使用计算的能力越来越重要。 传统上，地球科学学位课程不要求学生掌握重要的计算机编程和数据分析技能。 该项目将要求本科研究人员使用MATLAB科学编程环境进行数据挖掘，探索性数据分析和优化。 主要研究者将为学生提供这些技能的培训。该项目对地球化学以外的科学有影响，因此，由环境化学科学计划共同资助（NSF化学部）和跨学科的NSF计算和数据使能科学与工程计划。技术说明。在这个项目中，首席研究员巴里比克莫尔和他的小组将继续工作，创造一个简化的化学键模型，基于键价模型（BVM），可以很容易地转移到一个分子力学框架的原子模拟。 该模型中的势能项主要基于每个原子的键价的多极（双极、偶极和四极）展开。 这些术语往往是令人惊讶的可预测性，并描述了分子结构的所有主要方面，包括由于电子结构效应（孤对和Jahn-Teller）造成的扭曲。 它们本质上也是多体术语，描述了每个原子的总成键环境的各个方面，而不是专注于单个原子对。 这允许使用少量参数对非常复杂的相互作用进行建模。 目前的工作重点是开发键合模型来预测基于BVM的结构描述符的理想值，以及偏离理想值的能量成本函数。 此外，我们正在开发一些初步的分子力学力场，以进一步验证这一概念。 一些本科研究人员将参与该项目，并将学习计算机编程，数据分析和优化技术。