GOALI: Development of Transferable Force Fields for Phase Equilibria and Simulation Studies of Microheterogeneous Fluids and Crystalline Solids

准确了解复杂化学体系的相平衡和其他热物理性质具有巨大的基础和实际意义。分子模拟在预测热物理性质和推进我们对分子结构与宏观可观察物之间关系的理解方面的成功取决于有效的模拟算法和精确的力场的可用性。智力优势：力场发展。该项目的主要目标是推进由三个层次组成的相平衡可转移势力场（TraPPE）的发展。第一级（TraPPE UA）设计简单，计算效率高，精度好，并利用烷基段的联合原子表示。第二级（TraPPE EH）旨在提高非极性或弱极性化合物混合物的精度，明确包括烷基氢和一些孤对电子和键中心位点。第三级（TraPPE pol）仅针对尽可能高的准确性和可转移性，在这里，范德瓦尔斯和静电相互作用都可以响应环境的变化。建议将(i) TraPPE UA FF扩展到常见聚合物的构建块，（ii） TraPPE EH FF扩展到药物分子中的环，以及（iii） TraPPE pol FF扩展到水、烷烃、醇和醚。算法的发展。该项目还解决了新的蒙特卡罗方法，用于相平衡的第一性原理模拟和偏蒙特卡罗方法，以改善微非均质流体和结晶固体中相转移和空间分布的采样。应用程序。使用可转移力场的分子模拟将被用作工程工具来预测各种复杂系统的热物理性质，从而增加可用的实验数据库。模拟还将提供丰富的微观层面的洞察如何分子结构和组成决定宏观现象。特别是，将进行模拟以研究(i)微非均相流体中的溶剂化，（ii）含有非离子表面活性剂和普通低聚物的水混合物的界面和表面性质，以及（iii）药物固体的多态性和水合物形成。更广泛的影响。研究与教育的整合…通过将动手计算练习和分子模拟研究的局部结果结合起来，PI努力将他在大一的物质世界研讨会和研究生的热力学和统计力学课程的教学中注入发现的兴奋。PI以科学专家/联合主持人的身份参加了《科学工场》的液体和水！这是一个由美国国家科学基金会赞助的项目，旨在改善明尼阿波利斯公立学校的K8科学课程，并为三年级学生教授动手科学课程。人力资源开发。在大学产业伙伴关系的推动下，允许与博士进行广泛的互动。Ross和Schultz说，研究生教育可以以一种独特而成功的方式推进。此外，这项研究项目将促进本科生的参与，并将特别努力从传统上代表性不足的群体中招募这些学生。科学与工程基础设施。网络基础设施将通过通过网络界面和分子模拟软件包MCCCS（复杂化学系统蒙特卡罗）和Car-Parrinello 2000的开发来推进，这些软件包通过GNU通用公共许可证免费分发。

CBET-0756641SiepmannAccurate knowledge of the phase equilibria and other thermophysical properties of complex chemical systems is of enormous fundamental and practical importance. The success of molecular simulation in predicting thermophysical properties and in advancing our understanding of the relationship between molecular architecture and macroscopic observable, depends on the availability of efficient simulation algorithms and accurate force fields.Intellectual Merit: Force Field Development. The main goal of this project is to advance the development of the TraPPE (transferable potentials for phase equilibria) force field (FF) which consists of three levels. The first-level (TraPPE UA) is designed for simplicity and computational efficiency with good accuracy and makes use of united-atom representations for alkyl segments. The second level (TraPPE EH) is aimed at improved accuracy for mixtures of non-polar or weakly polar compounds and explicitly includes alkyl group hydrogens and some lone-pair electron and bond-center sites. The third level (TraPPE pol) is directed solely at the highest possible level of accuracy and transferability and here both the van der Waals and electrostatic interactions can respond to changes in the environment. It is proposed to extend (i) the TraPPE UA FF toward the building blocks of common polymers, (ii) the TraPPE EH FF toward rings found in pharmaceutical molecules, and (iii) the TraPPE pol FF to water, alkanes, alcohols, and ethers. Algorithm Development. This project also addresses novel Monte Carlo approaches for first principles simulations of phase equilibria and biased Monte Carlo methods to improve the sampling of phase transfers and spatial distributions in microheterogeneous fluids and crystalline solids. Applications. Molecular simulations using the transferable force fields will be employed as an engineering tool to predict thermophysical properties of a variety of complex systems, thereby adding to the available experimental database. The simulations will also provide a wealth of microscopic level insight into how molecular architecture and composition determine macroscopic phenomena. In particular, simulations will be carried out to investigate (i) solvation in microheterogeneous fluids, (ii) interfacial and surface properties of aqueous mixtures containing non-ionic surfactants and of common oligomers, and (iii) polymorphism and hydrate formation for pharmaceutical solids.Broader Impacts.Integration of Research and Education.. The PI strives to infuse his teaching of a freshman seminar on the material world and a graduate course on thermodynamics and statistical mechanics with the excitement of discovery by integrating hands-on computational exercises and topical results from molecular simulation research. The PI has participated as science expert/co-presenter for liquids and water in ScienceWorks!, an NSF-sponsored project that seeks to improve the Minneapolis Public Schools K8 science program, and taught hands-on science classes for third graders. Development of Human Resources. Driven by the university industry partnership, which allows for extensive interactions with Drs. Ross and Schultz of 3M Central Research, St. Paul, MN, the graduate student education can be advanced in a unique and successful way. In addition, this research project will foster the participation of undergraduate students and special efforts will be made to recruit these students from traditionally underrepresented groups. Science and Engineering Infrastructure. The cyberinfrastructure will be advanced by the development of the TraPPE force field made available via a web interface and of the molecular simulation packages MCCCS (Monte Carlo for Complex Chemical Systems) and Car-Parrinello 2000, which are freely distributed via GNU General Public Licenses.