GOALI: Development of Transferable Force Fields for Phase Equilibria and Simulation Studies of Aggregation and Solvation in Microheterogeneous Fluids

摘要目标：相平衡可转移力场的建立及微观非均相流体聚集和溶解的模拟研究准确了解复杂流体混合物的相平衡及其它热物理性质具有重要的理论意义和实际意义。分子模拟在预测热物理性质和推进我们对分子结构和宏观可观测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。 建议的研究的目标是发展三个层次的转移力场和偏置蒙特卡罗方法。一级力场，称为TraPPE UA（相平衡联合原子的可转移势），采用烷基链段的联合原子表示和简单的Lennard-Jones和库仑项。在第二个层次，称为TraPPE{EH（显式氢），所有的原子，包括烷基基团的氢和一些单对电子和键中心的网站显式处理。在第三个层次，称为TrapPE-pol（极化），无论是货车德瓦尔斯和静电相互作用可以响应环境的变化。而第一级是为了简单和计算效率与良好的准确性，第二级的目的是提高非极性或极性非氢键合化合物的混合物的准确性。第三个层次是完全针对最高水平的准确性和可转移性。 该项目将把TraPPE-UA力场扩展到炔;烯氧化物; 5元同芳环和杂芳环;卤代烃;伯、仲和叔氢氟醇、醚和氧化物;以及含硅和磷的官能团。TrapPE-EH力场将扩展到环状烷烃，烯烃和芳烃。TrapPE-pol力场的发展将继续与水，烷烃，醇类和醚类的共同参数。除了力场的发展，该项目还解决了相平衡的第一原理模拟的新模拟策略。使用transferableforce领域的分子模拟将被用作工程工具，以预测各种系统的热物理性质，从而增加到现有的实验数据库。这些模拟为复杂的化学系统提供了微观层面的信息，从而为分子结构和组成如何决定宏观现象提供了新的物理见解。特别是，模拟将进行调查（i）均匀成核现象，（ii）界面特性，聚集，并在含有非离子表面活性剂的混合物中的溶解度，和（iii）在单体/低聚物/聚合物系统的可溶解性。 拟议工作的更广泛影响包括开发可转移力场，高级算法和软件包，这些软件包通过印刷出版物，Web界面和GNU通用公共许可证免费提供。这些工具是一个大型研究社区热切期待的。此外，拟议项目将对各种教育、培训和辅导活动产生重大影响，并将使外联活动得以继续。 该项目将由一个紧密的大学-行业团队的广泛合作项目，该团队由PI，两名研究生以及明尼苏达州圣保罗3 M中央研究中心的Ross和考德威尔博士组成。

ABSTRACTGOALI: Development of Transferable Force Fields for Phase Equilibriaand Simulation Studies of Aggregation and Solvationin Microheterogeneous FluidsAccurate knowledge of the phase equilibria and other thermophysical properties of complex fluidmixtures 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. The goals of the proposed research are to develop three levels of transferable force fields and of biased Monte Carlo methods. The first-level force field, called TraPPE-UA (transferable potentials for phase equilibria united atom), employs the united-atom representation for alkyl segments and simple Lennard-Jones and Coulombic terms. In the second level, called TraPPE{EH (explicit hydrogen), all atoms including alkyl group hydrogens and somelone-pair electron and bond-center sites are treated explicitly. In the third-level, called TraPPE-pol (polarizable), both the van der Waals and electrostatic interactions can respond to changes in the environment. Whereas the first level is designed for simplicity and computational efficiency with good accuracy, the second level is aimed at improved accuracy for mixtures of non-polar or a polar non-hydrogen-bonding compounds. The third level is directed solely at the highest possible level of accuracy and transferability. The project will extend the TraPPE-UA force field to alkynes; alkene oxides; 5-membered homo- and hetero-aromatic rings; halogenated hydrocarbons; primary, secondary, and tertiary hydrofluoro alcohols, ethers, and oxides; and silicon and phosphorous containing functionalities. The TraPPE-EH force field will be extended to cyclic alkanes, alkenes, and arenes. An the development of the TraPPE-pol force field will be continued with common parameters for water, alkanes, alcohols, and ethers.In addition to force field development, this project also addresses novel simulation strategiesfor first principles simulations of phase equilibria. Molecular simulations using the transferableforce fields will be employed as engineering tool to predict thermophysical properties of a variety of systems, thereby adding to the available experimental database. The simulations provide microscopic-level information for complex chemical systems, thereby giving new physical insight into how molecular architecture and composition determine macroscopic phenomena. In particular, simulations will be carried out to investigate (i) homogeneous nucleation phenomena, (ii) interfacial properties, aggregation, and solubilities in mixtures containing non-ionic surfactants, and (iii) miscibility in monomer/oligomer/polymer systems. The broader impacts of the proposed work include the development of transferable force fields, advanced algorithms, and software packages that are made freely available through print publications, a web interface, and GNU General Public Licenses. These tools are eagerly awaited by a large research community. Furthermore, the proposed project will have a major impact on various educational, training, and mentoring activities and will allow continued outreach. This project will project from extensive collaboration of a tight university-industry team consisting of the PI, two graduate students, and Drs. Ross and Caldwell of 3M Central Research, St. Paul, MN.