Vester J, Despré V, Kuleff A I
Theoretische Chemie, PCI, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
J Chem Phys. 2023 Mar 14;158(10):104305. doi: 10.1063/5.0136681.
Due to the electron correlation, the fast removal of an electron from a molecule may create a coherent superposition of cationic states and in this way initiate pure electronic dynamics in which the hole-charge left by the ionization migrates throughout the system on an ultrashort time scale. The coupling to the nuclear motion introduces a decoherence that eventually traps the charge, and crucial questions in the field of attochemistry include how long the electronic coherence lasts and which nuclear degrees of freedom are mostly responsible for the decoherence. Here, we report full-dimensional quantum calculations of the concerted electron-nuclear dynamics following outer-valence ionization of propynamide, which reveal that the pure electronic coherences last only 2-3 fs before being destroyed by the nuclear motion. Our analysis shows that the normal modes that are mostly responsible for the fast electronic decoherence are the symmetric in-plane modes. All other modes have little or no effect on the charge migration. This information can be useful to guide the development of reduced dimensionality models for larger systems or the search for molecules with long coherence times.
由于电子关联，分子中电子的快速移除可能会产生阳离子态的相干叠加，从而引发纯电子动力学过程，在此过程中，电离留下的空穴电荷会在超短时间尺度内在整个系统中迁移。与核运动的耦合会引入退相干，最终捕获电荷，而阿秒化学领域的关键问题包括电子相干能持续多长时间以及哪些核自由度对退相干起主要作用。在此，我们报告了丙炔酰胺外层价电子电离后电子 - 核协同动力学的全维量子计算结果，结果表明纯电子相干在被核运动破坏之前仅持续2 - 3飞秒。我们的分析表明，对快速电子退相干起主要作用的简正模式是面内对称模式。所有其他模式对电荷迁移几乎没有影响或没有影响。这些信息有助于指导更大系统的降维模型的开发或寻找具有长相干时间的分子。
