The Development of Computational Methods to Study the Chemical Structural Evolution of Organic Macromolecules with Diagenesis

研究成岩有机大分子化学结构演化的计算方法进展

• 批准号: 9614352
• 负责人: George Cody
• 金额: $ 11.06万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-01-15 至 2000-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9614352&HistoricalAwards=false
• 关键词: Development; Computational; Methods; Study; Chemical

9614352 Cody Organic Reactions that modify the chemical structure of biomacromolecules are controlled, in part by the long range topology of the macromolecule. Understanding the role of macromolecular structure on monomer scale reactivity has important implications regarding our ability to assess the probability for preservation of ancient biomacromolecules (e.g. kerogen as a function of T, P, and fluid composition. The work defined in this proposal sets out to develop a methodology for computational organic geochemistry. A step-wise approach is outlined that starts with a statistical mechanical model of macromolecular topology (the Rotational Isomeric State Model). The rotational isomeric states are characterized through semi-empirical quantum mechanical calculations of the inter-segmental rotational energy surface. These calculations lead to the generation of a large scale, "coarse-grained" macromolecular model that includes the effects of over 10000, monomers. Construction of the macromolecular model is constrained by the RIS calculations; from the initial configuration, using a structure building algorithm, to the final equilibrium state obtained via Monte-Carlo methods. Two macromolecular systems are selected as initial problems. These are the diagenesis of lignin, a principle biomacromolecular component of the xylem tissue of wood, and the diagenesis of sporopollenin, a particularly resistant biopolymeric component of plant spores and seeds. The developed computational methods will be applied to assess the energetic penalties (or gains) of various proposed diagenetic reaction pathways in the two systems based on consideration of the total energy of the macromolecular system. The methodology obtained from the work outlined in this proposal will be exportable to a wide range of problems in organic geochemistry.

9614352 Cody 有机 改变生物大分子化学结构的反应部分受到大分子长程拓扑的控制。 了解大分子结构对单体规模反应性的作用对于我们评估古代生物大分子（例如干酪根作为 T、P 和流体成分的函数）保存概率的能力具有重要意义。本提案中定义的工作旨在开发概述了一种计算有机地球化学的方法，该方法从大分子拓扑的统计力学模型（旋转异构态模型）开始。段间旋转能量表面的半经验量子力学计算这些计算导致生成大规模的“粗粒度”大分子模型，其中包括超过 10000 个单体的影响。大分子模型的构建受到限制。通过 RIS 计算；从使用结构构建算法的初始配置到通过蒙特卡罗方法获得的最终平衡状态。 选择两个大分子系统作为初始问题。 这些是木质素的成岩作用（木材木质部组织的主要生物大分子成分）和孢粉质的成岩作用（植物孢子和种子的特别抗性的生物聚合成分）。 基于对大分子系统总能量的考虑，所开发的计算方法将用于评估两个系统中各种提出的成岩反应途径的能量损失（或增益）。 从本提案中概述的工作中获得的方法将可用于解决有机地球化学中的广泛问题。