Free rotor model or rigid rotor model for CH₃F-Ne complex and comparison with other CH₃F-rare gas systems

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• 作者：Yongtao Ma ; Yuanyuan Zhao ; Dan Hou ; Hui Li
• 关键词：Morse/long ; range model ; Rovibrational spectrum ; Symmetry ; top molecule ; CH3F ; Ne
• 刊名：Chemical Research in Chinese Universities
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：32
• 期：5
• 页码：818-826
• 全文大小：2,438 KB
• 刊物主题：Chemistry/Food Science, general; Analytical Chemistry; Inorganic Chemistry; Organic Chemistry; Physical Chemistry;
• 出版者：Springer Berlin Heidelberg
• ISSN：2210-3171
• 卷排序：32

文摘

The assignment of the rovibrational spectra of molecule-Ne complexes is always a challenge to study van der Waals systems, since they usually exhibit behavior intermediate between free rotor and rigid rotor. In this paper, the microwave and infrared spectra of CH₃F-Ne, a model system for symmetric-top-atom dimer, were firstly predicted and analyzed based on the four-dimensional ab initio intermolecular potential energy surfaces(PESs), which explicitly incorporate the v₃(C—F) stretch normal model coordinate of the CH₃F monomer. Analytic three-dimensional PESs were obtained by least-squares fitting vibrationally averaged interaction energies for v₃(CH₃F)=0 and 1 to the Morse/long-range(MLR) potential function for symmetry top impurity with atom model. These PESs fitting to 2340 points have root-mean-square(RMS) deviations of 0.07 cm–1, and require only 167 parameters. Based on the analytical vibrationally averaged PESs, the rovibrational energy levels were calculated by employing Lanczos algorithm, with combined radial discrete variable representation and parity-adapted angular finite basis representation. Based on the wavefunction analysis and comparison of CH₃F-Ne with CH₃F-He and CH₃F-Ar complexes, the bound states were assigned. Spectral parameters for CH₃F-Rg(Rg: rare gas, Rg=He, Ne, Ar) complexes were fitted and discussed. Temperature dependent transition intensities for CH₃F-Ne were also reported and analyzed. The complete microwave and infrared spectra information for CH₃F-Ne made it possible to provide important guidance for future experimental spectroscopic assignments.