Intermolecular potential and rovibrational states of the H₂O-D₂ complex

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• 作者：Ad van der Avoird^a ; ^{A.vanderAvoird@theochem.ru.nl} ; Yohann Scribano^b ; Alexandre Faure^c ; Miles J. Weida^d ; Joanna R. Fair^e ; David J. Nesbitt^f
• 关键词：Intermolecular potential ; Hydrogen bonding ; H2O ; Water ; H2 ; Rovibrational states ; Infrared spectrum
• 刊名：Chemical Physics
• 出版年：2012
• 期刊代码：18_03010104
• 类别：ch
• 出版时间：3 May, 2012
• 卷：399
• 期：Complete
• 页码：28-38
• 文件大小：1028 K

摘要

A five-dimensional intermolecular potential for H₂O-D₂ was obtained from the full nine-dimensional ab initio potential surface of Valiron et al. [P. Valiron, M. Wernli, A. Faure, L. Wiesenfeld, C. Rist, S. Ked啪uch, J. Noga, J. Chem. Phys. 129 (2008) 134306] by averaging over the ground state vibrational wave functions of H₂O and D₂. On this five-dimensional potential with a well depth D_e of 232.12 cm^鈭? we calculated the bound rovibrational levels of H₂O-D₂ for total angular momentum J = 0-3. The method used to compute the rovibrational levels is similar to a scattering approach鈥攊t involves a basis of coupled free rotor wave functions for the hindered internal rotations and the overall rotation of the dimer鈥攚hile it uses a discrete variable representation of the intermolecular distance coordinate R. The basis was adapted to the permutation symmetry associated with the para/ortho (p/o) nature of both H₂O and D₂, as well as to inversion symmetry. As expected, the H₂O-D₂ dimer is more strongly bound than its H₂O-H₂ isotopologue [cf. A. van der Avoird, D.J. Nesbitt, J. Chem. Phys. 134 (2011) 044314], with dissociation energies D₀ of 46.10, 50.59, 67.43, and 73.53 cm^鈭? for pH₂O-oD₂, oH₂O-oD₂, pH₂O-pD₂, and oH₂O-pD₂. A rotationally resolved infrared spectrum of H₂O-D₂ was measured in the frequency region of the H₂O bend mode. The ab initio calculated values of the rotational and distortion constants agree well with the values extracted from this spectrum.