We present a hybrid CCSD(T) + PBE-D3 approach to calculating the vibrational signatures for gas-phase benzene and benzene adsorbed on an ordered water ice surface. We compare the results of our method against experimentally recorded spectra and calculations performed using PBE-D3-only approaches (harmonic and anharmonic). Calculations use a proton ordered XIh water ice surface consisting of 288 water molecules, and results are compared against experimental spectra recorded for an ASW ice surface. We show the importance of including a water ice surface into spectroscopic calculations, owing to the resulting differences in vibrational modes, frequencies, and intensities of transitions seen in the IR spectrum. The overall intensity pattern shifts from a dominating ν11 band in the gas-phase to several high-intensity carriers for an IR spectrum of adsorbed benzene. When used for adsorbed benzene, the hybrid approach presented here achieves an RMSD for IR active modes of 21 cm−1, compared to 72 cm−1 and 49 cm−1 for the anharmonic and harmonic PBE-D3 approaches, respectively. Our hybrid model for gaseous benzene also achieves the best results when compared to experiment, with an RMSD for IR active modes of 24 cm−1, compared to 55 cm−1 and 31 cm−1 for the anharmonic and harmonic PBE-D3 approaches, respectively. To facilitate assignment, we generate and provide a correspondence graph between the normal modes of the gaseous and adsorbed benzene molecules. Finally, we calculate the frequency shifts, Δν, of adsorbed benzene relative to its gas-phase to highlight the effects of surface interactions on vibrational bands and evaluate the suitability of our chosen dispersion-corrected density functional theory.

中文翻译：

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有序水冰表面苯的振动性质

我们提出了一种混合 CCSD(T) + PBE-D3 方法来计算气相苯和吸附在有序水冰表面上的苯的振动特征。我们将我们方法的结果与实验记录的光谱和使用仅 PBE-D3 方法（谐波和非谐波）进行的计算进行比较。计算使用由 288 个水分子组成的质子有序 XIh 水冰表面，并将结果与​​ ASW 冰表面记录的实验光谱进行比较。由于在红外光谱中看到的振动模式、频率和跃迁强度的差异，我们展示了将水冰表面纳入光谱计算的重要性。对于吸附苯的 IR 光谱，整体强度模式从气相中的主要 ν11 带转变为几个高强度载流子。当用于吸附苯时，这里介绍的混合方法实现了 21 cm-1 的 IR 有源模式的 RMSD，而非谐波和谐波 PBE-D3 方法的 RMSD 分别为 72 cm-1 和 49 cm-1。与实验相比，我们的气态苯混合模型也取得了最佳结果，IR 主动模式的 RMSD 为 24 cm-1，而非谐波和谐波 PBE-D3 方法的 RMSD 为 55 cm-1 和 31 cm-1，分别。为了便于分配，我们生成并提供了气态和吸附苯分子的正常模式之间的对应图。最后，我们计算频移Δν，