Leboucher H, Simon A, Rapacioli M
Laboratoire de Chimie et Physique Quantiques LCPQ/FERMI, UMR5626, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France.
J Chem Phys. 2023 Mar 21;158(11):114308. doi: 10.1063/5.0139482.
Although clusters made of polycyclic aromatic hydrocarbon and water monomers are relevant objects in both atmospheric and astrophysical science, little is known about their energetic and structural properties. In this work, we perform global explorations of the potential energy landscapes of neutral clusters made of two pyrene units and one to ten water molecules using a density-functional-based tight-binding (DFTB) potential followed by local optimizations at the density-functional theory level. We discuss the binding energies with respect to various dissociation channels. It shows that cohesion energies of the water clusters interacting with a pyrene dimer are larger than those of the pure water clusters, reaching for the largest clusters an asymptotic limit similar to that of pure water clusters and that, although the hexamer and octamer can be considered magic numbers for isolated water clusters, it is not the case anymore when they are interacting with a pyrene dimer. Ionization potentials are also computed by making use of the configuration interaction extension of DFTB, and we show that in cations, the charge is mostly carried by the pyrene molecules.
尽管由多环芳烃和水单体组成的团簇在大气科学和天体物理学中都是相关的研究对象，但人们对它们的能量和结构性质知之甚少。在这项工作中，我们使用基于密度泛函的紧束缚（DFTB）势对由两个芘单元和一到十个水分子组成的中性团簇的势能面进行全局探索，随后在密度泛函理论水平上进行局部优化。我们讨论了相对于各种解离通道的结合能。结果表明，与芘二聚体相互作用的水团簇的凝聚能大于纯水团簇的凝聚能，对于最大的团簇，其渐近极限与纯水团簇相似，并且，尽管六聚体和八聚体对于孤立的水团簇可以被视为幻数，但当它们与芘二聚体相互作用时情况就不再如此。电离势也通过使用DFTB的组态相互作用扩展来计算，并且我们表明在阳离子中，电荷主要由芘分子携带。
