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密度函数理论计算了 Cu2 ,Ag2 和 Au2 二聚物的电子结构和光谱性质。结果表明 ,随着电子数的增加 ,相对论效应也在增加。使用 ZORA相对论方法可以得到可靠的电子结构。应用 B3 LYP作为交换 -相关函数 ,Cu2 ,Ag2 和 Au2 三个二聚物分子得到了相同的轨道能级顺序。在该族双分子化合物中全充满的 d电子不是完全惰性的。d电子在这三个分子当中对前线分子轨道的贡献也是完全不同的。同时由于 d电子和 s电子强相互作用引起 d型分子轨道的向上移动和 S型分子轨道向下移动。结果还表明 ,对于 Cu2 和 Au2 来说 ,d-型分子轨道和 S-型分子轨道的能级是非常接近的 ,这导致上述轨道在激发状态下很多相似的特性。而对于 Ag2 来说 ,d-型分子轨道和 S-型分子轨道能级较大的差表明 d电子对前线分子轨道只有极其微小的贡献。通过 TDDFT和 DSCF方法 ,确定和归属了低激发态的光谱项 ,并通过 s-和 d电子对这些激发态的贡献解释了光谱项的性质。目前研究得出的计算结果与实验数据非常吻合
The density functional theory calculated the electronic structure and spectral properties of Cu2, Ag2 and Au2 dimer. The results show that as the number of electrons increases, the relativistic effect also increases. Use the ZORA theory of relativity can get a reliable electronic structure. Using B3 LYP as the exchange-correlation function, Cu2, Ag2 and Au2 dimer molecules have the same Orbital order. Fully populated d-electrons in this family of bimolecular compounds are not completely inert. The contribution of electrons to the frontier molecular orbitals among the three molecules is also quite different. At the same time, the d-type molecular orbital moves upward and the S-type molecular orbit moves downward due to the strong interaction between d-electron and s-electron. The results also show that for Cu2 and Au2, the energy levels of the d-type molecular orbitals and the S-type molecular orbits are very close, resulting in many similar characteristics of the above orbit in the excited state. For Ag2, however, the large difference in energy levels between the d-type and S-type molecular orbitals indicates that d electrons make only a very small contribution to the frontier molecular orbitals. By TDDFT and DSCF methods, the spectra of low-excited states are identified and assigned and the properties of the spectra are explained by the contribution of s- and d-electrons to these excited states. The results of the current study are in good agreement with the experimental data