The Use of Computational Quantum Chemistry in Applied Thermodynamics

摘要CTS-0083709 S。这项研究的统一主题是利用现代计算化学来改进化学、生物化学和环境工业中使用的预测方法。现代计算量子力学在过去十年中在精度和速度方面都取得了快速发展，这主要是由于大规模，高度并行计算机的可用性。在很大程度上，化学工程界并没有利用这一进步。本计画主要针对计算量子化学在分子热力学三个领域的应用与利用：第一个领域是计算量子力学应用于基团贡献方法的改进;众所周知，这样的方法具有若干缺陷。 最重要的是邻近效应，其中官能团的行为受到同一分子上相邻基团的影响。这违反了基本的基团贡献概念，即官能团应该独立于其作为一部分的分子表现相同。在这里，人们概括了一个成功的，但到目前为止受到限制的混合量子力学/基团贡献模型，该模型已经开发出来，它基于每个基团的电荷和偶极矩如何因同一分子上的相邻基团而从参考状态变化来校正每个基团的性质和相互作用。第二个领域是应用量子化学方法计算两个分子之间的相互作用能景观，然后在Monte Carlo计算机模拟中将这些信息与非加性多体效应一起用于相互作用势函数。计算机模拟技术已经为分子水平的现象提供了大量的定性分析。 然而，模拟的定量准确性一直很差，除非在有效的两体势的经验参数已被拟合到实验数据。这部分研究的目标是确定化学工程师感兴趣的混合物的相行为是否可以使用最先进的多体势模型准确计算。第三个研究领域涉及使用上述混合物的量子化学/计算机模拟计算相结合的结果，以测试化学工程师传统上使用的活度系数模型的基本理论基础。目标是改进这些模型，并提供一种在缺乏实验数据的情况下确定这些模型中的参数的方法。

ABSTRACTCTS-0083709S. SandlerUniversity of DelawareThe unifying theme of the research is the use of modern computational chemistry to improve predictive methods used in the chemical, biochemical and environmental industries. Modern computational quantum mechanics has progressed rapidly in the last decade, both in terms of accuracy and speed, largely as a result of the availability of large-scale, highly parallel computers. To a large extent, the chemical engineering community has not taken advantage of this progress. This project is directed to the application and utilization of computational quantum chemistry in three areas of molecular thermodynamics.The first area of application of computational quantum mechanics is to the improvement of group contribution methods. It is well known that such methods suffer from several defects. The most important is the proximity effect in which the behavior of a functional group is affected by neighboring groups on the same molecule. This is a violation of the basic group contribution concept that a functional group should behave the same independent of the molecule of which it is a part. Here one generalize's a successful, but so far restricted hybrid quantum mechanics/group contribution model that had been developed that corrects the properties and interactions of each group based on how its charge and dipole moment vary from a reference state due to neighboring groups on the same molecule. The second area is the application of quantum chemistry methods to compute the interaction energy landscape between two molecules, and then to use this information in a interaction potential function together with nonadditive multibody effects in Monte Carlo computer simulation. Computer simulation techniques have provided a great deal of qualitative insight into molecular level phenomena. However, the quantitative accuracy of simulations have been poor unless the empirical parameters in the effective two-body potentials have been fit to experimental data. The goal of the this part of the research is to determine whether the phase behavior of mixtures of interest to chemical engineers can be accurately computed using state-of-the-art multibody potential models. The third research area involves the use of the results of combined quantum chemistry/computer simulation calculations for mixtures mentioned above to test the underlying theoretical basis of activity coefficient models traditionally used by chemical engineers. The goalis to improve upon these models, and to provide a method of determining the parameters in these models in the absence of experimental data.