Electronic Structure and Bonding in Molecular f Element Chemistry

对于包含f元素的分子的计算，相对论效应必须明确地包括在计算中，并且许多价原子轨道的近简并性导致许多紧密间隔的电子态。这些复杂性需要使用从头算波泛函理论（ab initio wave functional theory，WFT）来详细了解含f元素分子的电子结构。该项目的第一个重点是通式为EAnF 3的分子，其中E = N，P，As，Sb和Bi; An = U，Np和Pu。先前的计算表明，NUF 3、NNpF 3和NPuF 3具有三重An-N键;然而，其他电子态（对应于三重键中电子的非配对）计算出的能量非常接近。这些激发态可能与这些分子的实验振动光谱更好地匹配[Inorg.Chem.48（2009）6594]，因此真正的电子结构不清楚。最初的DFT计算给出了EUF 3的一个看似清晰的图像;在第15族（N：单线态; P，As：三线态; Sb，Bi：五重态）中增加了多重性，除了NUF 3（键级为3）之外，所有键级都为~1。这并不反映预测PUF 3和AsUF 3的单线态、三键结构的现有文献[Inorg.Chem.48（2009）6594]。从头计算将探讨这种差异。最初的DFT计算提出了一个相当不清楚的图片ENpF 3和EPuF 3，其中自旋污染是非常大的低多重数。开壳层电子基态是具有挑战性的DFT计算，所以WFT技术将被用来描述他们的结构。

For calculations on molecules containing f-elements, relativistic effects must be explicitly included in calculations and the near-degeneracy of many valence atomic orbitals results in many closely-spaced electronic states. These complications necessitate the use of ab initio wave functional theory (WFT) to obtain a detailed understanding of the electronic structure of f-element containing molecules.The first focus of the project is on molecules of the general formula EAnF3, where E = N, P, As, Sb and Bi; and An = U, Np, and Pu. Previous calculations suggest that NUF3, NNpF3 and NPuF3 have triple An-N bonds; however other electronic states (corresponding to the unpairing of electrons in the triple bond) are computed to be very close in energy. These excited states may match better with the experimental vibrational spectroscopy of these molecules [Inorg. Chem. 48 (2009) 6594], and so the true electronic structure is not clear. Initial DFT calculations present a seemingly clear picture for EUF3; increasing multiplicity down group 15 (N: singlet; P, As: triplet; Sb, Bi: quintet), with a bond order of ~1 for all but NUF3 (with a bond order of 3). This does not reflect existing literature which predicts singlet, triple-bonded structures for PUF3 and AsUF3 [Inorg. Chem. 48 (2009) 6594]. Ab initio calculations will be employed to explore this discrepancy.The initial DFT calculations present a considerably less clear picture for ENpF3 and EPuF3, where spin contamination is very large for low multiplicities. Open-shell electronic ground states are challenging to calculate with DFT, so WFT techniques will be employed to be able to describe their structures.