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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Systematic theoretical study of non-nuclear electron density maxima in some diatomic molecules
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Systematic theoretical study of non-nuclear electron density maxima in some diatomic molecules

机译：一些双原子分子中非核电子密度最大值的系统理论研究

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摘要

First, exploratory calculations were performed to investigate the presence of non-nuclear maxima (NNMs) in ground-state electron densities of homonuclear diatomic molecules from hydrogen up to calcium at their equilibrium geometries. In a second stage, only for the cases in which these features were previously detected, a rigorous analysis was carried out by several combinations of theoretical methods and basis sets in order to ensure that they are not only calculation artifacts. Our best results support that Li_2, B _2, C_2, and P_2 are molecules that possess true NNMs. A NNM was found in values obtained from the largest basis sets for Na _2, but it disappeared at the experimental geometry because optimized bond lengths are significantly inaccurate for this case (deviations of 0.10 ?). Two of these maxima are also observed in Si_2 with CCSD and large basis sets, but they are no longer detected as core-valence correlation or multiconfigurational wave functions are taken into account. Therefore, the NNMs in Si2 can be considered unphysical features due to an incomplete treatment of electron correlation. Finally, we show that a NNM is encountered in LiNa, representing the first discovery of such electron density maxima in a heteronuclear diatomic system at its equilibrium geometry, to our knowledge. Some results for LiNa, found in variations in internuclear distances, suggest that molecular electric moments, such as dipole and quadrupole, are sensitive to the presence of NNMs.
机译：首先，进行了探索性计算，以研究同核双原子分子在平衡态下从氢到钙的基态电子密度中非核最大值（NNM）的存在。在第二阶段中，仅对于先前已检测到这些特征的情况，通过理论方法和基础集的几种组合进行了严格的分析，以确保它们不仅是计算假象。我们的最佳结果支持Li_2，B_2，C_2和P_2是具有真正NNM的分子。从最大的Na _2基集获得的值中发现了NNM，但在实验几何上消失了，因为在这种情况下优化的键长明显不准确（偏差为0.10？）。在具有CCSD和较大基集的Si_2中也观察到了其中两个最大值，但是由于核心价相关或考虑了多构型波函数，因此不再检测到它们。因此，由于对电子相关性的不完全处理，Si2中的NNM可以认为是非物理特征。最后，我们证明在LiNa中遇到了NNM，这是我们所知，这是首次在异核双原子系统的平衡几何结构中发现这种电子密度最大值的现象。 LiNa的一些结果存在于核间距的变化中，表明分子电矩，例如偶极和四极，对NNM的存在很敏感。

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