Theoretical Analysis of Atmospheric Reactions

该项目涉及测试，扩展和应用高精度的理论方法，以大气化学反应。它包括三项任务。任务1是使用理论来预测含氮大气物种的反应速率常数和分支比。胺、亚胺和酰胺从饲养场和其他生物源排放。胺可能会导致未来的工业排放，因为它们是二氧化碳捕获（以减少温室气体排放）的工业方法的关键组成部分。由于含氮反应物的不稳定性，一些从未在实验上测量过的反应的速率常数将被预测。任务2是通过比较关键大气反应的预测速率常数与实验数据，进一步测试半经典过渡态理论（SCTST）的准确性。SCTST已经被证明可以预测从头算速率常数，与羟基自由基与分子氢反应的实验非常一致，而无需任何经验调整。它还预测从头算速率常数氯原子与甲烷在非常好的协议与实验。预测的氢/氘动力学同位素效应（KIEs）的两个反应是准确的现有的实验数据。SCTST将进一步表征，然后用于预测几个额外的大气反应的速率常数和KIE。任务3是扩展主方程处理单分子和重组反应明确纳入角动量守恒。这将显着改善现有的主方程，其中使用各种未经测试的近似，以避免显式处理。新的主方程将用于生成基准，并可用于预测速率常数和分析实验数据。气相化学动力学的所有领域都将受益于SCTST的表征。基准主方程计算将使其他研究人员能够测试碰撞和化学反应相互竞争的非平衡化学系统的模型。这些包括燃烧，化学制造，行星大气和天体化学。研究结果、参数化、源代码和所有模型将在科学会议上公布，发表在同行评议的文献中，并在互联网上免费提供。这些材料将增加大气化学的网络基础设施。学生和博士后研究助理将在开发和使用计算化学动力学方法的培训。

This project involves testing, extending, and applying high-accuracy theoretical methods to atmospheric chemical reactions. It consists of three tasks. Task 1 is to use theory to predict reaction rate constants and branching ratios for nitrogen-containing atmospheric species. Amines, imines, and amides are emitted from feedlots and other biogenic sources. Amines may contribute to future industrial emissions because they are key components of an industrial method for carbon dioxide capture (to reduce greenhouse gas emissions). Rate constants will be predicted for some reactions that have never been measured experimentally because the nitrogen-containing reactants are unstable. Task 2 is to further test the accuracy of Semi-Classical Transition Sate Theory (SCTST) by comparing predicted rate constants with experimental data for key atmospheric reactions. SCTST has already been shown to predict ab initio rate constants in excellent agreement with experiments for the reaction of hydroxyl radical with molecular hydrogen, without any empirical adjustments. It also predicts ab initio rate constants for chlorine atoms with methane in very good agreement with experiments. The predicted hydrogen/deuterium kinetic isotope effects (KIEs) for both reactions are as accurate as the existing experimental data. SCTST will be characterized further and then used to predict rate constant and KIEs for several additional atmospheric reactions. Task 3 is to extend the Master Equation treatment of unimolecular and recombination reactions by explicitly incorporating conservation of angular momentum. This will significantly improve on existing Master Equations, which use various untested approximations to avoid the explicit treatment. The new Master Equation will be used to generate benchmarks and can be used to predict rate constants and to analyze experimental data.All areas of gas phase chemical kinetics will benefit from the characterization of SCTST. The benchmark Master Equation calculations will enable other researchers to test models for non-equilibrium chemical systems where collisions and chemical reactions are competitive. These include combustion, chemical manufacturing, planetary atmospheres, and astrochemistry. The results, parameterizations, source codes, and all models will be presented at scientific meetings, published in the peer-reviewed literature, and made freely available on the internet. These materials will add to the cyberinfrastructure of atmospheric chemistry. Students and postdoctoral research associates will be trained in the development and use of computational chemical kinetics methods.