GOALI: Combining Discontinuous Molecular Dynamics and Chemical Process Simulation

摘要CTS-0075883 J。R Elliott在这个为期两年的探索性资助前景将被评估为整合分子建模工具与化学过程模拟包，以提供一个完整的，严格的，准确的框架，物理性质的预测和相关性。 化工过程模拟器正在成为工业化学知识的主要接口。 最近发现微扰理论比以前认识的精确得多，特别是对于多原子分子。 非连续分子动力学（DMD）模拟结合微扰理论和维里展开，为分子建模的各个方面提供了高度杠杆化的计算工作基础。 现有的DMD程序将在低成本微处理器上以合理的速度运行所需的最小数量的模拟。 所得的链段势模型将作为分子尺度的基团贡献，类似于传统的工程基团贡献模型。 虽然这些片段的潜在行为基本上作为第一组的贡献，从分子几何的高阶效应将明确解决通过用户指定的分子结构中的一阶基团的连接性，最初的目标将是测试的可移植性的不连续的潜在模型的平衡性质的纯流体和混合物。 一个数据库的波动群体的球体，二聚体，三聚体，6聚体，8聚体，和苯将被开发和用于开发最佳的步骤电位代表实验值的蒸汽压，密度，和内部能量的甲烷，乙烷，正己烷，正辛烷，苯，水，甲醇和乙醇。 所得到的潜力的可转移性将被评估的准确性方面的预测正丁烷，正戊烷，正庚烷，正壬烷，正癸烷。 对于混合物，将根据三元混合物和正丙醇+甲醇等混合物的预测准确性来评估可转移性，其中正丙醇中的羟基是专门回归的。第二个目标将是实施计算输运性质的方法，如粘度，热导率和扩散率，以及过去已经计算的平衡和共存性质。 由此产生的模拟将探讨在何种程度上，潜在的模型开发的基础上的平衡性能可以应用于估计运输性能。 它试图“解剖”模型分子间的潜在功能的意义上，确定哪些部分的潜力与特定的物理性质最强烈的相关性。 还寻求将是广泛适用的映射的吸引力的影响输运性能给定DMD模拟性能的参考流体，通过类比的扰动的角度平衡性能。 例如，在何种程度上可以预测的正癸烷的扩散性从相关的正辛烷和DMD模拟纯排斥正癸烷的扩散性的结果将被检查。 这项工作将与阿克伦大学和ChemStations，Inc.合作进行。 如果这种探索性的工作显示出希望，最终的目标将是一个互联网网站，客户端可以访问零成本的前面和相对较低的每小时费用根据服务器端计算的强度要求。 所提供的服务将包括运输和平衡性质的分子建模，如蒸汽压，活性，水溶性，辛醇分配系数，粘度，以及通过共同的分子模型从其他性质的测量中推断一种性质的能力。 在选项范围内将是一个全面的收集半经验的方法与估计的准确性，每一个属性。 该项目的范围包括对大约1300种化合物的数据库进行所有半经验模型和基于分子的模型的准确性的全面评估。 这些评价将构成探索阶段之后工作的很大一部分。 网络版还将包括基于快捷单元操作模型的流程图和工艺模拟。 工艺资本和生产成本对估计物理性质的敏感性将是一个菜单选项。 快捷模型将作为直接在基于网络的环境中进行严格流程模拟的先驱。

ABSTRACTCTS-0075883J. R ElliottIn this two-year exploratory grant prospects will be evaluated for integrating molecular modeling tools with a chemical process simulation package to provide a complete, rigorous, and accurate framework for physical property prediction and correlation. Chemical process simulators are becoming the primary interface for industry chemical knowledge. It has been recently discovered that perturbation theory is much more accurate than previously appreciated, especially for polyatomic molecules. Discontinuous molecular dynamics (DMD) simulation combines with perturbation theory and virial expansion to provide a basis for highly leveraged computational effort in all aspects of molecular modeling. An existing DMD program will run the minimal number of simulations necessary with reasonable speed on low-cost microprocessors. The resulting segmental potential models will act as molecular scale group contributions, analogous to conventional engineering group contribution models. Although these segmental potentials act essentially as first group contributions, higher order effects derived from molecular geometry will be explicitly addressed through the connectivity of the first order groups in the user-designated molecular structure.The initial goal will be to test the transferability of discontinuous potential models for the equilibrium properties of pure fluids and mixtures. A database of fluctuation populations for spheres, dimers, trimers, 6mers, 8mers, and benzene will be developed and be used to develop optimal step potentials for representing experimental values for vapor pressures, density, and internal energy for methane, ethane, n-hexane, n-octane, benzene, water, methanol and ethanol. The transferability of the resulting potentials will be evaluated in terms of the accuracy of predictions for n-butane, n-pentane, n-heptane, n-nonane, and n-decane. For mixtures, the transferability will be evaluated in terms of the accuracy of predictions for ternary mixtures and mixtures like n-propanol+methanol, for which the hydroxyl group in n-propanol was specifically regressed.The second goal will be to implement methods of calculating transport properties like viscosity, thermal conductivity, and diffusivity in addition to the equilibrium and coexistence properties that have been computed in the past. Resulting simulations will probe the extent to which potential models developed solely on the basis of equilibrium properties can be applied to estimating transport properties. It is sought to "dissect" model intermolecular potential functions in the sense of identifying which pieces of the potential correlate most strongly with specific physical properties. Also sought will be broadly applicable mappings of attractive effects on transport properties given DMD simulated properties for reference fluids, by analogy to the perturbation perspective for equilibrium properties. For example, the extent to which the diffusivity of n-decane can be predicted from correlated results for the diffusivity of n-octane and DMD simulations for purely repulsive n-decane will be examined. The work will be performed with collaboration between The University of Akron and ChemStations, Inc. If this exploratory work shows promise, the ultimate goal will be an internet site which clients can access for zero cost up front and relatively low hourly fees varying according to the intensity of the server side computation requested. Services provided will include molecular modeling of transport and equilibrium properties like vapor pressure, activity, water solubility, octanol partition coefficients, viscosity, and the ability to infer knowledge about one property from measurements of other properties through a common molecular model. Within the range of options will be a comprehensive collection of semi-empirical methods with estimates of the accuracy of each property. The scope of this project includes a thorough evaluation of the accuracy all the semi-empirical models and the molecular based models against a database of approximately 1300 compounds. Those evaluations will comprise a significant portion of the work beyond the exploratory phase. Also included in the web-accessible version will be flowsheeting and process simulation based on shortcut unit operation models. The sensitivity of the process capital and production costs to the estimated physical properties will be a menu option. The shortcut model will serve as a precursor for rigorous process simulations directly within a web-based environment.