Electronic Structure and Bonding in Molecular f Element Chemistry

对于含有f元素的分子的计算，相对论效应必须显式地包含在计算中，许多价原子轨道的近简并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(WFT)来详细了解含有f元素的分子的电子结构。该项目的第一个重点是通式为EAnF3的分子，其中E=N，P，As，Sb和Bi；An=U，Np和Pu。以前的计算表明，NUF3、NNpF3和NPuF3具有三个AN-N键；然而，其他电子态(对应于三个键中电子的不配对)在能量上非常接近。这些激发态可能与这些分子的实验振动光谱更好地匹配。化学。48(2009)6594]，因此真正的电子结构尚不清楚。最初的密度泛函计算给出了一幅EuF3的清晰图景；在第15族(N：单重态；P，As：三重态；Sb，Bi五重态)下增加多重数，除NUF3外，所有元素的键级均为~1(键级为3)。这并不反映现有文献预测PUF3和AsUF3的单线态、三键结构[Inorg.化学。48(2009)6594]。从头算将被用来探索这种差异。最初的密度泛函计算对ENpF3和EPuF3给出了一幅相当不清楚的图景，其中自旋污染对于低重数来说非常大。用密度泛函理论计算开壳层电子基态具有挑战性，因此将采用WFT技术来描述它们的结构。

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.