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

siepmann, Joern i .明尼苏达大学双城分校（university of Minnesota - Twin cities）对复杂流体混合物的相平衡和其他热物理性质的准确了解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促进我们对分子结构与宏观可观测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。研究的目标是继续发展三个层次的可转移力场和有偏差的蒙特卡罗方法。第一级力场称为trap - 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Lennar -Jones和Coulombic项。在第二级，称为TraPPE -EH（显氢），所有的原子，包括烷基氢和一些孤对电子和键中心位置都被明确处理。在第三层，称为trap -pol（极化），范德华和静电相互作用都可以对环境的变化做出反应。而第一级是为了简单和计算效率而设计的，具有良好的精度，第二级旨在提高非极性或极性非氢键化合物混合物的精度。第三个层次是针对尽可能高的准确性和可转移性。这些可转移的力场将包括线性、支链和环烷烃、烯烃、炔烃、烷基苯、醇、醚、酮、醛、酯、羧酸、胺、酰胺、腈、硫醇、硫化物、杂环、全氟烷烃，以及最后但并非最不重要的水。除了力场的发展，本提案还提出了针对固体-流体平衡、空间非均质混合物和氢键网络的有效模拟的新型模拟算法。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系统的热物理性质，从而增加可用的实验数据库。模拟还将为复杂的化学系统提供丰富的微观信息，从而为分子结构和组成如何决定宏观现象提供新的物理见解。特别是，将进行模拟以研究醇类在非极性溶剂中的结合、夹带剂对超临界流体中结构和溶解度的影响、加压对气胀液体的影响、高温高压下水和辛烷-1-醇之间的溶质分配、最低和最高沸点共沸混合物的结构、醇/水混合物的液-液平衡。药物及其钠衍生物的部分溶解度，以及溶剂对多晶体稳定性和溶剂化物形成的影响。该项目将受益于由PI和默克研究实验室的Sami Karaborni博士组成的紧密的大学-工业团队的广泛合作。

AbstractCTS-0138393Siepmann, Joern I.University of Minnesota - Twin CitiesAccurate knowledge of the phase equilibria and other thermophysical properties of complex fluid mixtures are of enormous fundamental and practical importance. The success of molecular simulation in predicting thermophysical properties an 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 research are to continue the development of 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 Lennar -Jones an Coulombic terms. In the second level, called TraPPE -EH (explicit hydrogen), all atoms including alkyl group hydrogens and some lone-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 apolar non-hydrogen-bonding compounds. The third level is directed solely at the highest possible level of accuracy and transferability. These transferable force fields will encompass linear, branched, and cyclic alkanes, alkenes, alkynes, alkylbenzenes, alcohols, ethers, ketones, aldehydes, esters, carboxylic acids amines, amides, nitriles, thiols, sulfides, heterocycles, perfluorinated alkanes, and last, but not least, water. In addition to the force field development, this proposal also addresses novel simulation algorithms which are targeted at efficient simulations of solid-fluid equilibria, spatially heterogeneous mixtures, and hydrogen-bonded networks.Molecular simulations using the transferable force fields will be employed as engineering tool topredict thermophysical properties of a variety of systems, thereby adding to the available experimental database. The simulations will also provide a wealth of 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 the association of alcohols in non-polar solvents, the influence of entrainers on structure and solubility in supercritical fluids, the effect of pressurization on gas-expanded liquids, the solute partitioning between water and octan-1-ol at elevated temperatures and pressures, the structures of minimum and maximum boiling azeotropic mixtures, the liquid-liquid equilibria of alcohol/water mixtures, the partial solubilities of drugs and their sodium derivatives, and the influence of solvents on the stability of polymorphs and on solvate formation.This project will profit from extensive collaboration of a close university-industry team consistingof the PI and Dr. Sami Karaborni of Merck Research Laboratories.