Theoretical studies of the N2O van der Waals dimer: ab initio potential energy surface, intermolecular vibrations and rotational transition frequencies.
Theoretical studies of the N2O van der Waals dimer: ab initio potential energy surface, intermolecular vibrations and rotational transition frequencies.
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DOI：
10.1063/1.3523984
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Limin Zheng;Yunpeng Lu;Soo-Y. Lee;H. Fu;Minghui Yang
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文献类型：
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作者：
Limin Zheng;Yunpeng Lu;Soo-Y. Lee;H. Fu;Minghui Yang
对N（2）O二聚体的势能面和束缚态进行了理论研究。采用aug-cc-pVTZ基组和键函数，在CCSD（T）水平上构造了一个四维分子间势能面.三个共面的局部极小值被发现在这个表面上。它们对应于一个具有滑动-反平行平面结构的非极性异构体和两个具有滑动-平行平面结构的等效极性异构体。非极性异构体在能量上比极性异构体稳定162 cm（-1）。为了分配这两种异构体的基本振动频率，超过150个振动束缚态计算基于此PES。波函数节面的取向在反旋和同旋振动模式的分配中起着重要的作用。计算得到的振动频率与实验数据符合得很好。在高振动激发态，我们还发现了两个等效极性结构之间的量子隧穿效应。计算了极性结构的转动跃迁频率。理论计算结果与实验结果吻合较好，验证了PES方法的准确性。
Theoretical studies of the potential energy surface and bound states were performed for the N(2)O dimer. A four-dimensional intermolecular potential energy surface (PES) was constructed at the CCSD(T) level with aug-cc-pVTZ basis set supplemented with bond functions. Three co-planar local minima were found on this surface. They correspond to a nonpolar isomer with slipped-antiparallel planar structure and two equivalent polar isomers with slipped-parallel planar structures. The nonpolar isomer is energetically more stable than the polar ones by 162 cm(-1). To assign the fundamental vibrational frequencies for both isomers, more than 150 vibrational bound states were calculated based on this PES. The orientation of the nodal surface of the wave functions plays an important role in the assignment of disrotation and conrotation vibrational modes. The calculated vibrational frequencies are in good agreement with the available experimental data. We have also found a quantum tunneling effect between the two equivalent polar structures in the higher vibrational excited states. Rotational transition frequencies of the polar structure were also calculated. The accuracy of the PES is validated by the good agreement between theoretical and experimental results for the transition frequencies and spectroscopic parameters.