Behaviour of DFT-Based Approaches to the Spin-Orbit Term of Zero-Field Splitting Tensors: A Case Study of Metallocomplexes, MIII(acac)3 (M = V, Cr, Mn, Fe and Mo)
Behaviour of DFT-Based Approaches to the Spin-Orbit Term of Zero-Field Splitting Tensors: A Case Study of Metallocomplexes, MIII(acac)3 (M = V, Cr, Mn, Fe and Mo)
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基于 DFT 的零场分裂张量自旋轨道项方法的行为：金属络合物 MIII(acac)3（M = V、Cr、Mn、Fe 和 Mo）的案例研究
DOI：
10.1039/c7cp05533a
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
T. Takui
中科院分区：
文献类型：
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作者：
K. Sugisaki;K. Toyota;K. Sato;D. Shiomi;T. Takui
自旋-轨道对零场分裂张量的贡献MIII（acac）3复合物的（DSO张量）（M = V、Cr、Mn、Fe和Mo; acac =乙酰丙酮根阴离子）通过从头算方法进行评价（混合CASSCF/MRMP 2）和DFT（Pederson-Khanna（PK）和基于自然轨道的Pederson-Khanna（NOB-PK））方法，着重于基于DFT的方法对DSO张量对八面体配位中过渡金属离子的价d-电子构型的行为。这两种基于DFT的方法都再现了D张量的趋势。值得注意的是，NOB-PK中的理论和实验D（D = DZZ −（DXX + DYY）/2）值之间的差异小于PK，强调了基于自然轨道的方法对过渡金属离子络合物D张量计算的有用性。在d2和d4电子组态的情况下，DSO（NOB-PK）值的绝对值被大大低估，与实验相比。基于轨道区域划分技术（ORPT）的DSO张量分析表明，DSO贡献归因于从单占据区域（SOR）的未占据区域（UOR）的激发显着低估的DFT为基础的方法，所有的复杂的研究。在d3和d5配置的情况下，（SOR → UOR）激励以几乎各向同性的方式贡献，这导致基于DFT的DSO值中的偶然误差消除。这些结果表明，更多的努力，发展DFT框架应针对再现的定量DSO张量的过渡金属配合物与各种电子配置和局部对称性周围的金属离子。
Spin–orbit contributions to the zero-field splitting (ZFS) tensor (DSO tensor) of MIII(acac)3 complexes (M = V, Cr, Mn, Fe and Mo; acac = acetylacetonate anion) are evaluated by means of ab initio (a hybrid CASSCF/MRMP2) and DFT (Pederson–Khanna (PK) and natural orbital-based Pederson–Khanna (NOB-PK)) methods, focusing on the behaviour of DFT-based approaches to the DSO tensors against the valence d-electron configurations of the transition metal ions in octahedral coordination. Both the DFT-based approaches reproduce trends in the D tensors. Significantly, the differences between the theoretical and experimental D (D = DZZ − (DXX + DYY)/2) values are smaller in NOB-PK than in PK, emphasising the usefulness of the natural orbital-based approach to the D tensor calculations of transition metal ion complexes. In the case of d2 and d4 electronic configurations, the DSO(NOB-PK) values are considerably underestimated in the absolute magnitude, compared with the experimental ones. The DSO tensor analysis based on the orbital region partitioning technique (ORPT) revealed that the DSO contributions attributed to excitations from the singly occupied region (SOR) to the unoccupied region (UOR) are significantly underestimated in the DFT-based approaches to all the complexes under study. In the case of d3 and d5 configurations, the (SOR → UOR) excitations contribute in a nearly isotropic manner, which causes fortuitous error cancellations in the DFT-based DSO values. These results indicate that more efforts to develop DFT frameworks should be directed towards the reproduction of quantitative DSO tensors of transition metal complexes with various electronic configurations and local symmetries around metal ions.