Development of High-Quality Models for Anhydrous and Aqueous Hydrogen Fluoride

[摘要]kofke， D. a . suny @ buffalo该项目关注的是能够预测和表征氟化氢（HF）及其与水的混合物的广泛性质的模型的发展。该项目的具体目标是开发和测试适合这些系统的分子模型。所有这些工作的更大目标是通过分子模拟将从头计算量子化学和体相建模连接起来的建模技术的进步。因此，项目的具体焦点为处理具有更广泛影响的问题提供了一种工具。该模型尽可能多地结合了控制分子相互作用的基本量子化学。研究了几种方法。第一种方法采用了目前广泛用于定量建模的方法。分散和排斥相互作用用12-6 exp-6模型处理，氢键通过简单的静电处理（例如，点电荷）建模。预计这种方法将失败，因为它没有捕捉到HF相互作用的重要特征。其他方法被认为包括高频中存在的量子力学效应，这些效应很难用分析势捕获。这些方法包括应用于水的量子力学和分子力学相结合的处理方法，以及明确考虑三体效应并与二聚体的高质量模型相结合的处理方法。然后将HF建模的进展介绍到水的分子模型中，以检查HF/水混合物的行为。通过检验其解释简单模型应用于已发表的实验HF/水气液平衡数据所得到的热力学不一致性的能力，来检验任何HF/水模型的有效性是有意义的。这里所有的建模工作都与体积性质、相平衡和热效应有关。HF在所有这些方向上的行为都是高度反常的。本研究的其他组成部分涉及分子间结合对表面张力的影响，以及对结合流体的改进分子模拟技术的发展。对前者的兴趣是由HF的异常小的表面张力驱动的，这有助于其形成气溶胶的能力（一个重要的安全问题），而后者的动机与应用于关联系统时模拟的自然低效率有关，结合我们对使用计算昂贵的分子模型研究此类系统的兴趣。

ABSTRACTCTS-0076515Kofke, D. A.SUNY @ BuffaloThis project is concerned with the development of models that can predict and characterize a broad range of properties of hydrogen fluoride (HF) and its mixtures with water. The specific aim of the project is to develop and test molecular models appropriate for these systems. The larger aim in all of this work is the advancement of modeling techniques that bridge ab initio quantum chemistry and bulk-phase modeling via molecular simulation. Thus the specific focus of the project provides a vehicle for treating a problem of much broader impact.The modeling incorporates as much as possible the fundamental quantum chemistry that governs the molecular interactions. Several approaches are examined. The first approach adopts methods that are currently in wide used for quantitative modeling. Dispersion and repulsive interaction are treated with 12-6 exp-6 models, and hydrogen-bonding is modeled via a simple electrostatic treatment (e.g., point charges). It is anticipated that this methodology will fail because it does not capture important features of HF interactions. Other approaches are considered to include the quantum-mechanical effects present in HF that are difficult to capture using an analytic potential. These include a combined quantum- and molecular-mechanics treatment that ahs been applied to water, and a treatment that considers three-body effects explicitly coupled with a high-quality model for the dimer. Advances in modeling of HF are then introduced to molecular models of water to examine the behavior of HF/water mixtures. It is of interest to test the validity of any HF/water model by examining its ability to explain the thermodynamic inconsistency obtained in the application of simple models to published experimental HF/water vapor-liquid equilibrium data.All modeling efforts here are concerned with the volumetric properties, phase equilibria and heat effects. The behavior of HF in all of these directions is highly anomalous. Additional components of this study are concerned with the effect of intermolecular association on surface tension, and on the development of improved molecular simulation techniques of associating fluids. The interest in the former is driven by the anomalously small surface tension of HF, which contributes to its ability to form aerosols (a significant safety problem), while the motivation for the latter is related to the natural inefficiency of simulation when applied to associating systems, combined with our interest in studying such systems with computationally expensive molecular models.