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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Potential energy surface for the benzene dimer and perturbational analysis of pi-pi interactions
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Potential energy surface for the benzene dimer and perturbational analysis of pi-pi interactions

机译：苯二聚体的势能面和pi-pi相互作用的微扰分析

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摘要

We present a complete 6-dimensional potential energy surface for the benzene dimer obtained using symmetry-adapted perturbation theory (SAPT) of intermolecular interactions based on Kohn-Sham's description of monomers. Ab initio calculations were performed for 491 dimer geometries in a triple-zeta-quality basis set supplemented by bond functions. An accurate analytic fit to the ab initio results has been developed and low-energy stationary points on the potential energy surface have been found. We have determined that there are three minima on the surface. Two of them, the tilted T-shape and the parallel-displaced, are nearly isoenergetic with interaction energies of -2.77 and -2.74 kcal/mol, respectively. The third minimum, a twisted edge-to-edge conformation, is significantly less attractive, with the interaction energy equal to -1.82 kcal/mol. Both the T-shape and sandwich geometries, sometimes assumed to be minima, are shown to be only saddle points. The potential energy surface is extremely flat between the two lowest minima, the barrier being only 0.10 kcal/mol above the global minimum. The second-virial coefficient obtained with the new potential agrees well with experimental results over a wide range of temperatures. The SAPT approach rigorously decomposes the interaction energy into physical components. The relative importance of these components has been analyzed.
机译：我们提出了一个完整的6维苯分子的6维势能面，该分子是使用基于Kohn-Sham对单体的描述的分子间相互作用的对称自适应扰动理论（SAPT）获得的。在由键函数补充的三元质量基础集中，对491个二聚体几何进行了从头算。对从头算的结果进行了精确的分析拟合，并发现了势能面上的低能平稳点。我们确定表面上有三个最小值。它们中的两个，即倾斜的T形和平行移动的，几乎是等能量的，相互作用能分别为-2.77和-2.74 kcal / mol。第三个最小值，即扭曲的边到边构型，吸引力极小，其相互作用能为-1.82 kcal / mol。 T型和三明治形的几何图形（有时被认为是极小值）仅显示为鞍点。势能表面在两个最低最小值之间极为平坦，势垒仅比全局最小值高0.10 kcal / mol。具有新潜力的二次病毒系数与在宽温度范围内的实验结果非常吻合。 SAPT方法将交互能量严格分解为物理组件。这些组件的相对重要性已被分析。

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