Department of Chemistry , University of Munich (LMU) , D-81377 Munich , Germany.
J Chem Theory Comput. 2018 Aug 14;14(8):4216-4223. doi: 10.1021/acs.jctc.8b00444. Epub 2018 Jul 18.
The equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) method with and without a complex absorbing potential (CAP) is applied for the study of the complex potential energy surfaces (CPES) of temporary anions and their parent neutral molecules. Crossings between the anionic state and the neutral state can be connected to the emission of nearly zero-energy electrons, which is demonstrated by the examples of acrylonitrile and methacrylonitrile. We show that the location of the minimum-energy crossing point (MECP) relative to the equilibrium structures of the neutral molecule and the anion can explain experimentally observed peaks on the threshold line of two-dimensional electron-energy loss spectra. The location and energy of the MECP is also crucial in dissociative electron attachment as we illustrate for chloro-substituted ethylenes. It is demonstrated that both the metastable region of the anionic CPES and the crossing with the neutral PES need to be considered to explain trends in the chloride ion formation cross sections of dichloroethylenes.
采用含时微扰耦合簇单双激发(EOM-CCSD)方法和含复变吸收势(CAP)的 EOM-CCSD 方法研究了瞬态阴离子及其母体中性分子的势能面(CPES)。阴离子态和中性态之间的交叉可以连接到近零能电子的发射，丙烯腈和甲基丙烯腈的例子证明了这一点。我们表明，相对于中性分子和阴离子的平衡结构，最低能量交叉点（MECP）的位置可以解释二维电子能量损失谱阈线上实验观测到的峰的位置。对于氯取代的乙烯，MECP 的位置和能量在电子离解中也起着至关重要的作用。结果表明，为了解释二氯乙稀的氯离子形成截面的趋势，需要同时考虑阴离子 CPES 的亚稳区和与中性 PES 的交叉。
