CDI-Type II: From Simulation Data to Mechanistic Understanding: Applications to Clathrate Hydrate Nucleation Mechanisms

CDI-Type II：从模拟数据到机理理解：笼形水合物成核机制的应用

• 批准号: 1125235
• 负责人: Amadeu Sum
• 金额: $ 60万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1125235&HistoricalAwards=false
• 关键词: CDI; Type; II; Simulation; Data

Amadeu Sum and David Wu, Colorado School of Mines (CSM), Gregg Beckham, CSM and National Renewable Energy Laboratory (NREL), Baron Peters , University of California, Santa Barbara and Valeria Molinero, University of Utah are supported by a CDI-TYPE II award to develop novel path sampling methods, based in statistical mechanics and information theory in order to collect and analyze data from large scale molecular simulations. These new techniques are being developed with the ultimate goal of elucidating the mechanism of clathrate hydrate nucleation. The specific aims are 1) to develop order parameters to identify ice and clathrate hydrate structures; 2) develop the Packet Evolution Path Sampling (PEPS) method; and 3) apply PEPS to simpler systems to demonstrate the utility of the method. The order parameters are a key component this effort as they provide physical insight and quantify the mechanisms of nucleation. The new sampling method (PEPS) provides a more efficient method of sampling and extracting mechanistic details on nucleation by harvesting the evolution along a 'reaction coordinate.' Lennard-Jones liquid-to-solid nucleation and water-to-ice nucleation are the testing systems to demonstrate the first application of the methods which will then be applied to clathrate hydrates nucleation. The methods themselves, however, are generally and may be used to gain understanding from molecular simulations of a variety of complex phenomena.Understanding transition mechanisms in real systems is a daunting problem for molecular simulation, both in terms of efficient data collection and analysis. There is a need for transformative new methods that can be applied to realistic systems and huge data sets that are now commonplace with increasing computing power. One specific motivating problem where new path sampling methods can be applied is to the mechanism of clathrate hydrate nucleation. Clathrate hydrates, ice-like compounds formed from hydrogen-bonded water cages surrounding small non-polar molecules such as methane or carbon dioxide, have gained interest for their importance in energy (hydrates are present at the ocean floor in quantities estimated to be at least twice that of known oil and gas reserves; conversely, plugging of pipelines by gas hydrate formation poses the primary flow assurance problem to the oil and gas industry, as well as an impedance in the containment of a deepwater oil/gas blowout) and the environment (carbon sequestration and methane release from natural hydrate deposits). In a broader context for the application to hydrate nucleation, fundamental knowledge will be gained in nucleation theory, understanding arising from hydrophobic and hydrophilic interactions, and new approaches for structural quantification. Insight into the molecular mechanism for hydrate nucleation may be transformative because it will be constructing knowledge from microscopic interactions to macroscopic behavior, as opposed to current approaches where the reverse is predominant.

科罗拉多矿业学院（CSM）的Amadeu Sum和大卫吴、加州大学圣巴巴拉分校的Gregg Beckham和国家可再生能源实验室（NREL）的Baron Peters以及犹他州大学的Valeria Molinero获得了CDI-TYPE II奖的支持，以开发基于统计力学和信息论的新型路径采样方法，以收集和分析大规模分子模拟的数据。 这些新技术的发展最终目的是阐明笼形水合物成核的机理。 具体目标是：1）开发顺序参数，以识别冰和笼形水合物结构; 2）开发包演化路径采样（PEPS）方法;和3）应用PEPS到更简单的系统，以证明该方法的实用性。有序参数是这项工作的关键组成部分，因为它们提供了物理见解并量化了成核机制。新的采样方法（PEPS）提供了一个更有效的方法，采样和提取成核机理的细节收获的演变沿着a '反应坐标。Lennard-Jones液-固成核和水-冰成核是证明这些方法的首次应用的测试系统，然后将其应用于笼形水合物成核。 然而，这些方法本身通常并且可以用于从分子模拟中获得对各种复杂现象的理解。理解真实的系统中的转变机制对于分子模拟来说是一个艰巨的问题，无论是在有效的数据收集还是分析方面。需要有一种变革性的新方法，可以应用于现实的系统和巨大的数据集，这些数据集现在随着计算能力的提高而变得司空见惯。一个具体的激励问题，其中新的路径采样方法可以应用是笼形水合物成核的机制。笼形水合物是一种冰状化合物，由氢键结合的水笼围绕着小的非极性分子（如甲烷或二氧化碳）形成，由于其在能源中的重要性而引起了人们的兴趣（海底水合物的数量估计至少是已知石油和天然气储量的两倍;相反，由于气体水合物形成而造成的管道堵塞给石油和天然气工业带来了主要的流动保证问题，以及深水石油/天然气井喷的遏制中的阻抗）和环境（碳封存和天然水合物沉积物的甲烷释放）。在水合物成核应用的更广泛背景下，将获得成核理论的基础知识，从疏水和亲水相互作用中产生的理解，以及结构量化的新方法。深入了解水合物成核的分子机制可能是变革性的，因为它将构建从微观相互作用到宏观行为的知识，而不是目前的方法，相反的是占主导地位。