Tan Jake A, Kuo Jer-Lai
Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Da-an District, Taipei City 10617, Taiwan.
J Chem Phys. 2021 Apr 7;154(13):134302. doi: 10.1063/5.0044703.
Matrix isolation experiments have been successfully employed to extensively study the infrared spectrum of several proton-bound rare gas complexes. Most of these studies have focused on the spectral signature for the H stretch (ν) and its combination bands with the intermolecular stretch coordinate (ν). However, little attention has been paid to the Fermi resonance interaction between the H stretch (ν) and H bend overtone (2ν) in the asymmetric proton-bound rare gas dimers, RgHRg'. In this work, we have investigated this interaction on KrHRg and XeHRg with Rg = (Ne, Ar, Kr, and Xe). A multilevel potential energy surface (PES) was used to simulate the vibrational structure of these complexes. This PES is a dual-level comprising of second-order Møller-Plesset perturbation theory and coupled-cluster singles doubles with perturbative triples [CCSD(T)] levels of ab initio theories. We found that when both the combination bands (nν + ν) and bend overtone 2ν compete to borrow intensity from the ν band, the latter wins over the former, which then results in the suppression of the nν + ν bands. The current simulations offer new assignments for the ArHXe and KrHXe spectra. Complete basis set (CBS) binding energies for these complexes were also calculated at the CCSD(T)/CBS level.
矩阵隔离实验已成功用于广泛研究几种质子键合稀有气体配合物的红外光谱。这些研究大多集中在H伸缩振动（ν）及其与分子间伸缩坐标（ν）的组合带的光谱特征上。然而，对于不对称质子键合稀有气体二聚体RgHRg'中H伸缩振动（ν）和H弯曲泛频（2ν）之间的费米共振相互作用，关注较少。在这项工作中，我们研究了Rg = （Ne、Ar、Kr和Xe）时KrHRg和XeHRg中的这种相互作用。使用多能级势能面（PES）来模拟这些配合物的振动结构。这个PES是一个双能级的，由二阶Møller-Plesset微扰理论和耦合簇单双激发并带有微扰三激发[CCSD(T)]的从头算理论能级组成。我们发现，当组合带（nν + ν）和弯曲泛频2ν都竞争从ν带借用强度时，后者胜过前者，这就导致了nν + ν带的抑制。当前的模拟为ArHXe和KrHXe光谱提供了新的归属。还在CCSD(T)/CBS水平计算了这些配合物的完全基组（CBS）结合能。
