Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are believed to be widespread in different areas of the interstellar medium. However, the astronomical detection of specific aromatic molecules is extremely challenging. As a result, only a few aromatic molecules have been identified, and very little is known about how they are formed in different areas of the interstellar medium. Recently, McGuire et al. [Science 359, 202–205 (2018)] detected the simple aromatic molecule benzonitrile in Taurus Molecular Cloud-1. Although benzonitrile has been observed, the molecular mechanism for its formation is still unknown. In this study, we use quantum chemistry and ab initio molecular dynamics to model ionization processes of van der Waals clusters containing cyanoacetylene and acetylene molecules. We demonstrate computationally that the clusters' ionization leads to molecular formation. For pure cyanoacetylene clusters, we observe bond formation among two and three monomer units, whereas in mixed clusters, bond formation can also occur in up to four units. We show that the large amount of energy available to the system after ionization can lead to barrier crossing and the formation of complex molecules. Our study reveals the rich chemistry that is observed upon ionization of the clusters, with a wide variety of molecules being formed. Benzonitrile is among the observed molecules, and we study the potential energy path for its formation. These results also offer insights that can guide astronomers in their search for aromatic molecules in the interstellar medium.

多环芳香烃和多环芳香氮杂环被认为广泛存在于星际介质的不同区域。然而，特定芳香族分子的天文检测极具挑战性。因此，只有少数芳香族分子被鉴定出来，而且对于它们如何在星际介质的不同区域中形成知之甚少。最近，麦圭尔等人。[科学359, 202–205 (2018)] 在 Taurus Molecular Cloud-1 中检测到简单的芳香分子苯甲腈。尽管已经观察到苯甲腈，但其形成的分子机制仍然未知。在这项研究中，我们使用量子化学和从头分子动力学来模拟包含氰基乙炔和乙炔分子的范德华簇的电离过程。我们通过计算证明簇的电离导致分子形成。对于纯氰乙炔簇，我们观察到两个和三个单体单元之间的键形成，而在混合簇中，键形成也可能发生在多达四个单元中。我们表明，电离后系统可用的大量能量会导致跨越势垒和复杂分子的形成。我们的研究揭示了在簇电离时观察到的丰富的化学物质，形成了各种各样的分子。苯腈是观察到的分子之一，我们研究了其形成的势能路径。这些结果还提供了可以指导天文学家在星际介质中寻找芳香分子的见解。