The quantum mechanics of small molecules nanoconfined in complex chemical environments

复杂化学环境中纳米限制小分子的量子力学

• 批准号: 1566085
• 负责人: Zlatko Bacic
• 金额: $ 50万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1566085&HistoricalAwards=false
• 关键词: quantum; mechanics; small; molecules; nanoconfined

In this project funded by the Chemical Structure, Dynamics and Mechanisms A program in the Division of Chemistry, Professors Zlatko Bacic and Mark Tuckerman of New York University are performing theoretical calculations on molecules confined in cages formed by other molecules, or within a single C60 "Buckyball" molecule. They are interested in understanding how molecules such as water (H2O), hydrogen (H2) and other small molecules move when they are in restricted spaces. This theoretical study will improve the interpretation of experimental measurements, for example the results of a technique called inelastic neutron scattering (INS). It will also have implications for the control of material properties at the molecular level (for advanced "nanoelectronics" applications), and possibly for the design of efficient and economical hydrogen storage media for energy technologies. Two graduate students are directly involved as researchers in this project. The conceptual advances and new results from this research will be integrated into educational materials for undergraduates. Finally, methodology developments achieved in this project will be incorporated into the Principal Investigators' user-friendly software tools that will be made freely available to the general community.An array of sophisticated theoretical and computational approaches, some developed in the realization of this project, ranging from multidimensional bound-state and scattering methods to path-integral molecular dynamics (PIMD) simulations, is implemented in these investigations. The INS spectra of H2O confined in C60 are calculated with high accuracy utilizing the newly developed methodology for quantum simulation of the INS spectra of nanoconfined polyatomic molecules. The PIMD simulations of the crystalline H2O in C60, an extraordinary 3D cubic lattice of highly quantum H2O dipoles, each confined inside C60, shed light on its dielectric properties and free energetics, including the ferroelectric phase transition, arising from the many-body dipolar correlations. Path-integral simulations also probe the temperature and pressure dependence of the free energetics and approximate diffusion rates of H2 and D2 molecules in the sII clathrate hydrates, simple and binary, accounting for quantum effects and framework flexibility. These studies address the fundamental problem of the diffusion of molecular hydrogen in the quantum regime, inside a chemically and structurally complex environment. Quantum treatment of the condensed-phase effects, including the proton disorder of the framework water molecules, on the "rattling" dynamics and the INS spectra of H2 in the sII clathrate hydrate addresses the general question of how the dynamical and spectroscopic properties of guest molecules inside a host environment evolve and approach their bulk limits.

在这个由化学结构、动力学和机制A项目资助的项目中，纽约大学的Zlatko Bacic和Mark塔克曼教授正在对被其他分子形成的笼中或单个C60“巴克球”分子内的分子进行理论计算。 他们有兴趣了解分子，如水（H2O），氢（H2）和其他小分子在受限空间中如何移动。这一理论研究将改善对实验测量结果的解释，例如一种称为非弹性中子散射（INS）的技术的结果。 它还将对在分子水平上控制材料特性（用于先进的“纳米电子学”应用）产生影响，并可能对能源技术中高效经济的储氢介质的设计产生影响。 两名研究生作为研究人员直接参与了这个项目。 这项研究的概念进展和新成果将被整合到本科教育材料中。最后，在本项目中取得的方法发展将纳入主要研究人员的用户友好的软件工具，这些工具将免费提供给公众。一系列复杂的理论和计算方法，其中一些是在实现本项目的过程中开发的，从多维束缚态和散射方法到路径积分分子动力学（PIMD）模拟，在这些调查中实施。利用新开发的纳米限制多原子分子INS光谱量子模拟方法，高精度地计算了C60中限制的H2O的INS光谱。晶体H2O在C60中的PIMD模拟，C60是高度量子化的H2O偶极子的非凡的3D立方晶格，每个都被限制在C60内，揭示了其介电性质和自由能，包括铁电相变，由多体偶极相关引起。路径积分模拟还探测温度和压力的依赖性的自由能和近似的扩散速率的H2和D2分子在SII笼形水合物，简单和二元，占量子效应和框架的灵活性。这些研究解决了分子氢在量子体系中扩散的基本问题，在化学和结构复杂的环境中。的凝聚相的影响，包括质子无序的框架水分子，对“嘎嘎作响”的动力学和INS光谱的H2在SII笼形水合物的量子治疗地址的一般问题，如何动态和光谱性质的客人分子内的主机环境的演变和接近他们的散装限制。