Garden Anna L, Halonen Lauri, Kjaergaard Henrik G
Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
J Phys Chem A. 2008 Aug 14;112(32):7439-47. doi: 10.1021/jp802001g. Epub 2008 Jul 18.
We have calculated the band profiles of the OH-stretching fundamental and overtone transitions in the proton donor unit of the water dimer complex. We have used a local mode Hamiltonian that includes both OH-stretching and OO-stretching motion but separates these adiabatically. The variation of OH-stretching frequency and anharmonicity with OO displacement from equilibrium contributes to the effective OO-stretching potentials for each OH-stretching state. The resulting OO-stretching energy levels and wave functions are used to simulate the vibrational profile of each OH-stretching transition. The coupled cluster with singles, doubles, and perturbative triples ab initio method with an augmented triple-zeta correlation consistent basis set has been used to obtain the necessary parameters, potentials, and dipole moment functions. We find that the OO-stretching transitions associated with a given hydrogen bonded OH-stretching transition are spread significantly and this spread increases with overtone. The spread is minor for the free OH-stretching transition. The inclusion of the OO-stretching mode has a limited effect on the overall OH-stretching band intensity.
我们计算了水二聚体复合物质子供体单元中OH伸缩基频和倍频跃迁的能带分布。我们使用了一种局域模哈密顿量，它既包括OH伸缩运动，也包括OO伸缩运动，但将它们绝热分离。OH伸缩频率和非谐性随OO相对于平衡位置位移的变化，对每个OH伸缩态的有效OO伸缩势有贡献。由此得到的OO伸缩能级和波函数用于模拟每个OH伸缩跃迁的振动分布。采用含单双激发和微扰三激发的耦合簇从头算方法，并使用了一个增强的三ζ相关一致基组来获得必要的参数、势和偶极矩函数。我们发现，与给定氢键OH伸缩跃迁相关的OO伸缩跃迁分布显著，且这种分布随倍频增加。对于自由OH伸缩跃迁，这种分布较小。包含OO伸缩模式对整体OH伸缩带强度的影响有限。
