Bonding Nature and Vibrational Signatures of Oxirane:(Water)n=1鈥?. Assessment of the Performance of the Dispersion-Corrected DFT Methods Compared to the ab initio Results and Fourier

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• 作者：M. Cirtog ; M. E. Alikhani ; B. Madebe虁ne ; P. Soulard ; P. Asselin ; B. Tremblay
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：June 23, 2011
• 年：2011
• 卷：115
• 期：24
• 页码：6688-6701
• 全文大小：1004K
• 年卷期：v.115,no.24(June 23, 2011)
• ISSN：1520-5215

文摘

Spectroscopic properties of 1:n complexes (n = 1, 2, and 3) formed between an oxirane molecule and water clusters have been evaluated using experimental techniques (FTIR spectroscopy using a new supersonic jet experiment coupled to the infrared AILES beamline of synchrotron SOLEIL and also cryogenic neon matrix device) and theoretical approaches (SAPT, ab initio, DFT, and topological analyses). From a systematic comparison between the theoretical results (obtained with both wave function based methods and several newly hydrogen bonded adapted functionals) with the available experimental results on the studied compounds, it was concluded that only the wave function based methods (particularly coupled clusters ones) are able to well describe these compounds, while the newly hydrogen bonded adapted functionals (long-range and/or dispersion-corrected ones and also double hybrids) cannot adequately describe all the spectroscopic properties in a systematic way. The MP2 method, although more expensive than DFT, still offers a reliable method to study both isolated molecules and hydrogen bonded complexes provided the contribution of the dispersion energy in total energy is properly taken into account. The nature of interaction between oxirane and water molecules has been analyzed using the symmetry adapted perturbation theory (SAPT) method. It was evidenced that the water鈥搊xirane interaction corresponds to the hydrogen-bonded systems with a large contribution of the dispersion energy. The nature of the oxirane鈥搘ater bonding has been studied using two topological methods: atoms in molecules and electron-localization function (ELF). Geometrical structures of the titled complexes were rationalized from the spatial arrangement of ELF attractors. Secondary interaction was also accounted for the bond critical points found at H_oxirane路路路O_water bond paths.