Koopman Jeroen, Grimme Stefan
Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany.
ACS Omega. 2019 Sep 5;4(12):15120-15133. doi: 10.1021/acsomega.9b02011. eCollection 2019 Sep 17.
In this work, we have tested two different extended tight-binding methods in the framework of the quantum chemistry electron ionization mass spectrometry (QCEIMS) program to calculate electron ionization mass spectra. The QCEIMS approach provides reasonable, first-principles computed spectra, which can be directly compared to experiment. Furthermore, it provides detailed insight into the reaction mechanisms of mass spectrometry experiments. It sheds light upon the complicated fragmentation procedures of bond breakage and structural rearrangements that are difficult to derive otherwise. The required accuracy and computational demands for successful reproduction of a mass spectrum in relation to the underlying quantum chemical method are discussed. To validate the new GFN2-xTB approach, we conduct simulations for 15 organic, transition-metal, and main-group inorganic systems. Major fragmentation patterns are analyzed, and the entire calculated spectra are directly compared to experimental data taken from the literature. We discuss the computational costs and the robustness (outliers) of several calculation protocols presented. Overall, the new, theoretically more sophisticated semiempirical method GFN2-xTB performs well and robustly for a wide range of organic, inorganic, and organometallic systems.
在这项工作中，我们在量子化学电子电离质谱（QCEIMS）程序框架内测试了两种不同的扩展紧束缚方法，以计算电子电离质谱。QCEIMS方法提供了合理的、基于第一性原理计算的光谱，可直接与实验进行比较。此外，它还能深入了解质谱实验的反应机制。它揭示了难以通过其他方式推导的键断裂和结构重排的复杂碎片化过程。讨论了成功再现质谱相对于基础量子化学方法所需的精度和计算要求。为了验证新的GFN2-xTB方法，我们对15个有机、过渡金属和主族无机体系进行了模拟。分析了主要的碎片化模式，并将整个计算光谱直接与文献中的实验数据进行比较。我们讨论了所提出的几种计算协议的计算成本和稳健性（异常值）。总体而言，新的、理论上更复杂的半经验方法GFN2-xTB在广泛的有机、无机和有机金属体系中表现良好且稳健。
