Automated Construction of Potential Energy Surfaces Suitable to Describe van der Waals Complexes With Highly-Excited Nascent Molecules: The Rotational Spectra of Ar–CS( v ) and Ar–SiS( v )
Automated Construction of Potential Energy Surfaces Suitable to Describe van der Waals Complexes With Highly-Excited Nascent Molecules: The Rotational Spectra of Ar–CS( v ) and Ar–SiS( v )
复制标题
自动构建适合描述具有高激发新生分子的范德华配合物的势能面：Ar-CS( v ) 和 Ar-SiS( v ) 的旋转光谱
DOI：
10.1021/acs.jpca.0c02685
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
McCarthy, Michael C
中科院分区：
文献类型：
--
作者：
Quintas-Sánchez, Ernesto;Dawes, Richard;Lee, Kelvin;McCarthy, Michael C
某些反应产生极热的新生产物，然而这些产物可以与浴气中的原子或分子形成足够长寿命的货车德瓦耳斯（vdW）络合物，如通过微波光谱学所观察到的。这种非束缚共振态的理论计算可能比普通的束缚态计算更具挑战性，这取决于所采用的方法。人们遇到的不只是软盘，也许multiwelled势能面（PES）特性的vdWs复合物，但此外，人们必须抗衡激发的分子内模式及其相应的影响PES。简单计算感兴趣的（共振）振转能级，涉及波函数的未束缚性质的额外复杂性，通常用诸如引入复杂吸收势的技术来处理。在这里，我们已经证明，一个简化的方法，使一系列的振动有效的PES的分子间的坐标-一个为每个反应产物的振动量子数的兴趣-可以产生vdW水平的复杂的光谱精度。这需要构建一系列适当加权的低维PES，我们使用我们免费提供的PES拟合代码AUTOSURF。本研究的应用是Ar-CS和Ar-SiS络合物，它们与Ar-CO和Ar-SiO是等价的，后者我们在以前的研究中考虑过。使用一系列的振动有效的PES，振转能级和预测的微波跃迁频率为这两个复杂的变分计算。一系列的移位旋转跃迁频率也被计算作为硅藻振动量子数的函数。预测的转变被用来指导和通知实验的努力，使互补的意见。比较给出的范围内的光谱仪，并成功地记录的过渡。的振转能级模式的计算同意在0.2%以内的实验测量。
Some reactions produce extremely hot nascent products which nevertheless can form sufficiently long-lived van der Waals (vdW) complexes—with atoms or molecules from a bath gas—as to be observed via microwave spectroscopy. Theoretical calculations of such unbound resonance states can be much more challenging than ordinary bound-state calculations depending on the approach employed. One encounters not just the floppy, and perhaps multiwelled potential energy surface (PES) characteristic of vdWs complexes, but in addition, one must contend with excitation of the intramolecular modes and its corresponding influence on the PES. Straightforward computation of the (resonance) rovibrational levels of interest, involves the added complication of the unbound nature of the wave function, often treated with techniques such as introducing a complex absorbing potential. Here, we have demonstrated that a simplified approach of making a series of vibrationally effective PESs for the intermolecular coordinates—one for each reaction product vibrational quantum number of interest—can produce vdW levels for the complex with spectroscopic accuracy. This requires constructing a series of appropriately weighted lower-dimensional PESs for which we use our freely available PES-fitting code AUTOSURF. The applications of this study are the Ar–CS and Ar–SiS complexes, which are isovalent to Ar–CO and Ar–SiO, the latter of which we considered in a previously reported study. Using a series of vibrationally effective PESs, rovibrational levels and predicted microwave transition frequencies for both complexes were computed variationally. A series of shifting rotational transition frequencies were also computed as a function of the diatom vibrational quantum number. The predicted transitions were used to guide and inform an experimental effort to make complementary observations. Comparisons are given for the transitions that are within the range of the spectrometer and were successfully recorded. Calculations of the rovibrational level pattern agree to within 0.2% with experimental measurements.