Computational Chemistry for Fluids Confined in Nanoporous Materials

摘要该提案要求继续资助一项成功的研究计划，该计划涉及纳米多孔材料中流体的计算化学。在这项研究中，我们从量子力学开始，以获得准确的力场之间的吸附分子和纳米多孔材料，然后使用这些力场在平衡（蒙特卡罗）和动态（分子动力学）模拟预测吸附，渗透性，和分离因子的气体，离子和药物分子在两个新的类别的纳米多孔材料：金属有机框架和稳定的蛋白质晶体。的方法和结果有可能产生重大影响的设计和开发的新的纳米多孔材料的工程和生物工程分离technology.Intellectual Merit：由于几何限制和接近的表面，流体在纳米多孔材料表现出一系列丰富的相现象和扩散速率，显着不同的散装流体。计算机模拟为理解这种行为提供了有用的工具。目前在这一领域的研究一般使用经验力场，例如，对于碳材料，通过关联在平面石墨上测量的吸附行为来开发。然而，从模拟中获得的结果非常依赖于所使用的力场，并且我们从我们的研究中了解到，由于高度弯曲的表面，键应变，环结构和杂化的差异，碳纳米结构材料中吸附物经历的力场与平面石墨表面上的力场非常不同。正是由于这个原因，我们将不使用经验势，而是使用第一性原理的层次方法，从力场的量子力学发展开始，然后（使用模拟）预测宏观行为。四个具体的智力目标是：1）进一步发展先进的计算方法，以获得原子分辨率，时间分辨的洞察力的微观行为的限制流体在纳米结构材料;2）发展精确的力场量子化学的客体流体在纳米多孔基板，然后预测平衡和动态3）开发用于研究限制在任何类型的纳米多孔基底中的流体的普遍适用的方法;以及4）详细研究两种最近开发的纳米多孔材料，金属有机框架和稳定（通过交联）蛋白质晶体中的吸附和传输。更广泛的影响：了解限制在纳米多孔材料，有机和无机纳米管，血管和细胞中的流体行为在催化，纳米电子学，生物系统和其他新兴技术领域非常重要。在这个计划中，我们将结合量子化学计算和分子模拟，研究各种物理和化学现象，如吸附，运输，相变，和化学反应，在两个最近开发的新型纳米多孔材料，金属有机框架和蛋白质晶体。更好的分子水平的理解所涉及的现象可以帮助在无机，有机和生理通道和毛细管中的流体的准确描述，以及在设计和优化定制的纳米多孔材料的气体存储，分离，用作分子筛和催化剂载体的特定应用，以及相关领域。我们将通过使用最先进的计算化学来开发精确的力场，然后将其用于复杂程度不断增加的真实的系统。

AbstractThis proposal requests fund for the continuation of a successful research program on thecomputational chemistry for fluids confined in nanoporous materials. In this research, we start with quantum mechanics to obtain accurate force fields between adsorbing molecules and nanoporous materials, and then use these force fields in equilibrium (Monte Carlo) and dynamic (molecular dynamics) simulations to predict adsorption, permeability, and separation factors of gases, ions, and pharmaceutical molecules in two new classes of nanoporous materials: metal-organic frameworks andstabilized protein crystals. The methodology and results have the potential to have a significant impact on the design and development of new nanoporous materials for engineering and bioengineering separation technologies.Intellectual Merit: Due to the geometric confinement and proximity of the surface, fluids in nanoporous materials exhibit a range of rich phase phenomena and diffusion rates that are significantly different from those of bulk fluids. Computer simulation provides a useful tool for understanding such behavior. Current research in this area has generally used empirical force fields, e.g., for carbon materials, developed by correlating measured adsorption behavior on planar graphite. However, results obtained from simulation are very dependent on the force field used, and we have learned from our research that asa result of the highly curved surfaces, bond strains, differences in ring structure and hybridization, the force field an adsorbate experiences in a carbon nanostructured material is very different from that on a planar graphite surface. It is for this reason that instead of using empirical potentials, we will use a firstprinciples hierarchal approach of starting from the quantum mechanical development of a force field, andproceeding (using simulation) to the prediction of macroscopic behavior. Four specific intellectual goals are:1) to further develop advanced computational approaches to obtain atomic-resolution, time-resolved insights into the microscopic behavior of confined fluids in the nanostructured materials;2) to develop accurate force fields from quantum chemistry for guest fluids in the nanoporous substrates, and then to predict equilibrium and dynamic (transport) properties of interest in engineering;3) to develop a generally applicable method for the study of fluids confined in any type of nanoporous substrate; and4) to examine in detail adsorption and transport in two recently developed nanoporous materials, metal-organic frameworks and stabilized (by cross linking) protein crystals.Broader Impact: Understanding the behavior of fluids confined in nanoporous materials, organic and inorganic nanotubes, vessels, and cells is important in catalysis, nanoelectronics, biological systems, and in other emerging technology areas. In this proposal, by integrating quantum chemical calculations and molecular simulations, we will investigate various physical and chemical phenomena such as adsorption,transport, phase transitions, and chemical reactions in two recently developed novel nanoporous materials, metal-organic frameworks and protein crystals. Better molecular-level understanding of the phenomena involved can help in developing accurate descriptions of the fluids in inorganic, organic and physiologic channels and capillaries, as well as in the design and optimization of tailored nanoporous materials for specific applications in gas storage, separations, for use as molecular sieves and catalystsupports, and related areas. We will do this by using state-of-the-art computational chemistry to develop accurate force fields that will then be used for real systems of increasing degree of complexity.