使用电子结构方法研究二甲基硫化物 (DMS) 和Cl在缺水和存在水的情况下发生的大气相关反应
Lydia Rhyman1,2, Edmond P F Lee3, Ponnadurai Ramasami1,2
1Computational Chemistry Group, Department of Chemistry, Faculty of Science, University of Mauritius, Réduit 80837, Mauritius. lyd.rhyman@gmail.com.
Physical chemistry chemical physics : PCCP
|July 16, 2025
概括
这项研究研究了二甲基硫化物 (DMS) 和分子 (Cl2) 之间的反应,有和没有水. 水的存在使反应机制复杂化,但在热层条件下不会显著改变总体速率系数.
科学领域:
- 大气化学 大气化学
- 化学动力学 化学动力学
- 计算化学计算化学
背景情况:
- 硫化二甲基 (DMS) 是一个重要的大气硫化合物.
- 分子 (Cl2) 是一个重要的大气氧化剂.
- 了解DMS和Cl2之间的反应对于大气建模至关重要.
研究的目的:
- 研究DMS + Cl2反应的热力学和机制.
- 探索单个水分子对反应路径的影响.
- 在大气条件下确定反应动力学.
主要方法:
- 利用电子结构方法,包括密度函数理论 (DFT) 与M06-2X函数和aug-cc-pVTZ基础集.
- 采用基于域的局部对自然轨道合集群[DLPNO-UCCSD(T]方法进行高精度的能量计算.
- 范德瓦尔斯复杂的形成和反应路径的计算平衡常数.
主要成果:
- 反应可以通过三个初始的范德瓦尔斯复合物进行:DMS + Cl2·H2O,DMS·H2O + Cl2或DMS·Cl2 + H2O.
- 在大气条件下,预计DMS·H2O和Cl2·H2O复合物比DMS·Cl2.2更丰富.
- 确定了两个主要的反应途径,涉及共价结合或 cis-中间体,其中水显著改变了潜在能量图.
- 尽管水带来了机械复杂性,但总体DMS+Cl2速率系数在热带层不太可能受到影响.
结论:
- 水的存在影响了DMS与Cl2的反应机制,但对热层的总速率系数的影响微不足道.
- 这项研究提供了对反应途径和热力学的详细见解,扩展了以前对DMS与原子反应的研究.
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