Atmospheric Kinetics: Bimolecular Reactions of Carbonyl Oxide by a Triple-Level Strategy.
Atmospheric Kinetics: Bimolecular Reactions of Carbonyl Oxide by a Triple-Level Strategy.
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DOI：
10.1021/jacs.1c02029
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发表时间：
2021-05
影响因子：
15
通讯作者：
Bo Long;Ying Wang;Yu Xia;Xiao He;J. Bao;D. Truhlar
中科院分区：
文献类型：
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作者：
Bo Long;Ying Wang;Yu Xia;Xiao He;J. Bao;D. Truhlar
Criegee中间体在大气中作为氧化剂启动气溶胶的形成，这是特别重要的大气建模，了解他们的动力学是当前突出的挑战之一，在气候变化建模。由于实验动力学仍然是有限的，我们必须依靠理论的全貌，但从理论获得绝对速率是一项艰巨的任务。在这里，我们报告的双分子反应动力学的羰基氧与氨，硫化氢，甲醛，和水二聚体通过设计一个三层次的战略，结合（i）基准结果接近完整的基础限制耦合集群理论与单，双，三，四重激发（CCSDTQ/CBS），（ii）一种新的杂合Meta密度泛函（M06 CR），其特别优化用于Criegee中间体的反应，和（iii）变分过渡态理论与可变的反应坐标和优化的反应路径，与多维隧道，并与压力的影响。对于（i），我们发现需要四重激发来获得定量反应势垒，并且我们设计了新的复合方法和策略来达到CCSDTQ/CBS精度。结果表明：（i）在宽的大气条件下，CH_2OO + HCHO反应对HCHO的汇有重要贡献;（ii）在10 km以下，CH_2OO+（H_2O）_2反应对HCHO的汇起主导作用。
Criegee intermediates in the atmosphere serve as oxidizing agents to initiate aerosol formation, which are particularly important for atmospheric modeling, and understanding their kinetics is one of the current outstanding challenges in climate change modeling. Because experimental kinetics are still limited, we must rely on theory for the complete picture, but obtaining absolute rates from theory is a formidable task. Here, we report the bimolecular reaction kinetics of carbonyl oxide with ammonia, hydrogen sulfide, formaldehyde, and water dimer by designing a triple-level strategy that combines (i) benchmark results close to the complete-basis limit of coupled-cluster theory with the single, double, triple, and quadruple excitations (CCSDTQ/CBS), (ii) a new hybrid meta density functional (M06CR) specifically optimized for reactions of Criegee intermediates, and (iii) variational transition-state theory with both variable rection coordinates and optimized reaction paths, with multidimensional tunneling, and with pressure effects. For (i) we have found that quadruple excitations are required to obtain quantitative reaction barriers, and we designed new composite methods and strategies to reach CCSDTQ/CBS accuracy. The present findings show that (i) the CH2OO + HCHO reaction can make an important contribution to the sink of HCHO under wide atmospheric conditions in the gas phase and that (ii) CH2OO + (H2O)2 dominates over the CH2OO + H2O reaction below 10 km.