在国家重大需求和学术前沿领域从事化学理论与机制的基础理论研究。聚焦关键催化过程的核心科学问题，围绕甲烷、水和氮气等惰性小分子的活化与转化，以量子化学计算为工具，在创造新分子、发现新反应、建立新机制、提出新理论方面取得系列原创性成果：

    在理论层面率先构建高价氧络铁调控的C-H键活化完整机制图像；首次发现甲烷双氢协同转移机制，在离子/分子反应中率先引入外电场概念；从电子结构层面阐释氢转移机制的多样性、规律性及机制间相互转变微观本质；氢原子转移机制先决条件的再认识等。此外，在瞬时中间体、催化活性物等方面也取得标志性成果。

代表作：

[1] Caiyun Geng, Jilai Li*, Thomas Weiske, Helmut Schwarz*. Complete Cleavage of the N≡N Triple Bond by Ta₂N⁺ via Degenerate Ligand Exchange at Ambient Temperature: A Perfect Catalytic Cycle Proc. Natl. Acad. Sci. USA 2019, 116, 21416–21420. DOI: 10.1073/pnas.1913664116

[2] Caiyun Geng, Thomas Weiske, Jilai Li*, Sason Shaik*, Helmut Schwarz*. Intrinsic Reactivity of Diatomic 3d Transition-Metal Carbides in the Thermal Activation of Methane: Striking Electronic Structure Effects. J. Am. Chem. Soc. 2019, 141, 599-610. DOI: 10.1021/jacs.8b11739

[3] Caiyun Geng, Jilai Li*, Thomas Weiske, Helmut Schwarz*. Ta₂⁺ Mediated Ammonia Synthesis from N₂ and H₂ at Ambient Temperature. Proc. Natl. Acad. Sci. USA 2018, 115, 11680-11687. DOI: 10.1073/pnas.1814610115

[4] Caiyun Geng, Jilai Li*, Thomas Weiske, Helmut Schwarz*. Thermal O–H Bond Activation of Water as Mediated by Heteronuclear [Al₂Mg₂O₅]^•+: Evidence for Oxygen-Atom Scrambling. J. Am. Chem. Soc. 2018, 140, 9275-9281. DOI: 10.1021/jacs.8b05618

[5] Caiyun Geng, Jilai Li*, Thomas Weiske, Maria Schlangen, Sason Shaik*, Helmut Schwarz*. Electrostatic and Charge-Induced Methane Activation by a Concerted Double C–H Bond Insertion. J. Am. Chem. Soc. 2017, 139, 1684-1689. DOI: 10.1021/jacs.6b12514

[6] Caiyun Geng, Shengfa Ye, Neese, Frank*. Analysis of Reaction Channels for Alkane Hydroxylation by Nonheme Iron(IV)-oxo Complexes. Angew. Chem. Int, Ed. 2010, 49, 5717-5720. DOI :10.1002/anie.201001850