Karimi-Jafari Mohammad H, Maghari Ali
Department of Physical Chemistry, School of Chemistry, University of Tehran, Tehran, Iran.
J Phys Chem A. 2007 Jul 12;111(27):6077-83. doi: 10.1021/jp071413q. Epub 2007 Jun 15.
Two analytical representations for the potential energy surface of the F(2) dimer were constructed on the basis of ab initio calculations up to the fourth-order of Møller-Plesset (MP) perturbation theory. The best estimate of the complete basis set limit of interaction energy was derived for analysis of basis set incompleteness errors. At the MP4/aug-cc-pVTZ level of theory, the most stable structure of the dimer was obtained at R = 6.82 au, theta(a) = 12.9 degrees , theta(b) = 76.0 degrees , and phi = 180 degrees , with a well depth of 716 microE(h). Two other minima were found for canted and X-shaped configurations with potential energies around -596 and -629 microE(h), respectively. Hexadecapole moments of monomers play an important role in the anisotropy of interaction energy that is highly R-dependent at intermediate intermolecular distances. The quality of potentials was tested by computing values of the second virial coefficient. The fitted MP4 potential has a more reasonable agreement with experimental values.
基于高达四级莫勒-普莱斯特定理（MP）微扰理论的从头算计算，构建了F₂二聚体势能面的两种解析表示。为分析基组不完备误差，推导了相互作用能完整基组极限的最佳估计值。在MP4/aug-cc-pVTZ理论水平下，二聚体最稳定结构在R = 6.82 au、θ(a) = 12.9°、θ(b) = 76.0°和φ = 180°时获得，阱深为716微hartree。还发现了另外两个极小值，分别对应倾斜和X形构型，势能分别约为-596和-629微hartree。单体的十六极矩在相互作用能的各向异性中起重要作用，在中等分子间距离时，这种各向异性高度依赖于R。通过计算第二维里系数的值来测试势能的质量。拟合的MP4势能与实验值有更合理的一致性。
