Theorectical Studies of van der Waals Molecules

该项目得到了NSF理论和计算科学中心的支持。 化学程序，研究分子间的现象， 交互. 特拉华州大学的Krzysztof Szalewicz教授 和合作者将进一步提高适应性扰动 理论（SAPT）开发的二聚体相互作用，和一个新的版本 将导出适用于三聚体的方法。 这一理论允许透明 分子间势能的物理解释 基本相互作用：静电、交换、感应和 分散体 该理论没有基组叠加问题， 在计算上比超分子多体理论更有效 微扰理论方法 高级计算 最先进的分子间势能面， 实验相关的货车范德瓦尔斯二聚体和三聚体将 执行。 这些研究将有助于了解真实的 形成货车德瓦耳斯键的物理机制和 物理相互作用导致了极小值，隧道效应 势垒和电势的各向异性。 这项工作预计将 帮助解释实验数据，特别是在以下情况下 三体非加性 该项目的一个重要部分将 涉及旨在解决该领域当前问题的应用程序 关于稀有气体原子与各种分子的相互作用， 氮、二氧化碳、水或氨，以及它们的二聚体 分子。 三聚体将包括稀有气体原子Ar 2-HF，和 水三聚体当前对三体的理论认识 互动是非常不令人满意的，特别是考虑到最近的 这一领域的实验活动。 SAPT方法提供了 非相加性物理分析和获得的可能性 精确的数值。 本项目研究的现象之间的相互作用 分子。 这些相互作用比化学作用力弱得多 分子中的结合原子，负责广泛的 物理，化学和生物现象：从水的沸腾 遗传密码 标准的计算化学方法， 在描述化学键方面非常成功，但在 描述这些分子间的力。 Szalewicz和合作者将 开发和使用基于量子力学的严格方法， 这些系统的描述，以提供更完整的 理解这些分子间的相互作用。

This project, supported by the NSF Theoretical and Computational Chemistry Program, investigates the phenomenon of intermolecular interactions. Prof. Krzysztof Szalewicz of the University of Delaware and collaborators will further improve symmetry-adapted perturbation theory (SAPT) developed by them for dimer interactions, and a new version applicable to trimers will be derived. This theory allows transparent physical interpretation of intermolecular potentials in terms of four fundamental interactions: electrostatic, exchange, induction, and dispersion. The theory is free from basis set superposition problems and is computationally more efficient than the supermolecular many-body perturbation theory approach. High-level calculations of state-of-the-art intermolecular potential energy surfaces for experimentally relevant van der Waals dimers and trimers will be performed. These studies will help provide an understanding of the real physical mechanism for the formation of van der Waals bonds and the physical interactions that are responsible for minima, tunneling barriers, and anisotropies of the potentials. This work is expected to assist interpretation of experimental data, particularly in the case of three-body nonadditivities. An important part of the project will involve applications aimed at resolving current problems in the field concerning interactions of rare gas atoms with various molecules such as nitrogen, carbon dioxide, water, or ammonia, as well as dimers of those molecules. The trimers will include rare gas atoms, Ar2-HF, and the water trimer. The current theoretical understanding of three-body interactions is very unsatisfactory, in particular in view of recent experimental activity in this field. The SAPT method offers the possibility of physical analysis of nonadditivities and of obtaining accurate numerical values for them. This project investigates the phenomenon of interactions between molecules. These interactions, much weaker than the chemical forces binding atoms in molecules, are responsible for an extensive range of physical, chemical, and biological phenomena: from the boiling of water to the genetic code. Standard computational chemistry methods, which are very successful in describing chemical bonds, are inadequate in describing these intermolecular forces. Szalewicz and collaborators will develop and use rigorous methods based on a quantum mechanical description of these systems in order to provide a more complete understanding of these molecular interactions.