The European Physical Journal D ( IF 1.5 ) Pub Date : 2020-11-01 , DOI: 10.1140/epjd/e2020-10081-0 Léo Dontot 1 , Fernand Spiegelman 1 , Sébastien Zamith 2 , Mathias Rapacioli 1
|
Abstract
Infrared spectra are computed for neutral and cationic clusters of Polycyclic Aromatic Hydrocarbon molecules, namely \( {({\mathrm{C}}_{16}{\mathrm{H}}_{10})}_{n=\mathrm{1,4}}^{(0/+)}\), using the Density Functional based Tight Binding scheme combined with a Configuration Interaction (DFTB-CI) in the double harmonic approximation. Cross-comparison is carried out with DFT and simple DFTB. Similarly to the monomer cation, the IR spectra of cluster cations are characterized by a depletion of the intensity of the CH stretch modes around 3000 cm−1, with a weak revival for n = 3 and 4. The in-plane CCC modes in the region 1400–2000 cm−1 are enhanced while the CH bending modes in the range 700–1000 cm−1 are significantly weakened with respect to the monomer cation, in particular for n = 2. Finally, soft modes corresponding to diedral fluctuations of the monomers within the central stack of the ion structure, possibly mixed with monomer folding, are also observed in the region 70–120 cm−1.
Graphical abstract
中文翻译：
小多环芳烃簇的振动光谱对电荷的依赖性：芘的例子
摘要
计算多环芳烃分子的中性和阳离子簇的红外光谱，即\( {({\mathrm{C}}_{16}{\mathrm{H}}_{10})}_{n=\mathrm {1,4}}^{(0/+)}\)，使用基于密度泛函的紧绑定方案与双谐波近似中的配置交互（DFTB-CI）相结合。与DFT和简单DFTB进行交叉比较。与单体阳离子类似，簇阳离子的红外光谱的特征是 CH 拉伸模式在 3000 cm -1附近的强度耗尽， n = 3 和 4 时有微弱的恢复。相对于单体阳离子，1400–2000 cm -1范围内的 CH 弯曲模式得到增强，而 700–1000 cm -1范围内的 CH 弯曲模式显着减弱，特别是当n = 2 时。最后，对应于在 70-120 cm -1区域也观察到离子结构中心堆叠内的单体，可能与单体折叠混合。
京公网安备 11010802027423号