Influence of Water on Anharmonicity, Stability, and Vibrational Energy Distribution of Hydrogen-Bonded Adducts in Atmospheric Reactions: Case Study of the OH + Isoprene Reaction Intermediate Using Ab

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• 作者：Scott M. Dietrick ; Alexander B. Pacheco ; Prasad Phatak ; Philip S. Stevens ; Srinivasan S. Iyengar
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：January 12, 2012
• 年：2012
• 卷：116
• 期：1
• 页码：399-414
• 全文大小：784K
• 年卷期：v.116,no.1(January 12, 2012)
• ISSN：1520-5215

文摘

The effect of water on the stability and vibrational states of a hydroxy-isoprene adduct is probed through the introduction of 1鈥?5 water molecules. It is found that when a static nuclear harmonic approximation is invoked there is a substantial red-shift of the alcohol O鈥揌 stretch (of the order of 800 cm^鈥?) as a result of introduction of water. When potential energy surface sampling and associated anharmonicities are introduced through finite temperature ab initio dynamics, this hydroxy-isoprene OH stretch strongly couples with all the water vibrational modes as well as the hydroxy-isoprene OH bend modes. A new computational technique is introduced to probe the coupling between these modes. The method involves a two-dimensional, time-frequency analysis of the finite temperature vibrational properties. Such an analysis not only provides information about the modes that are coupled as a result of finite-temperature analysis, but also the temporal evolution of such coupling.