Fitzhugh Henry C, Furness James W, Pederson Mark R, Peralta Juan E, Sun Jianwei
Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, United States.
Department of Physics, The University of Texas at El Paso, El Paso, Texas 79968, United States.
J Chem Theory Comput. 2023 Sep 12;19(17):5760-5772. doi: 10.1021/acs.jctc.3c00336. Epub 2023 Aug 15.
Multicenter transition-metal complexes (MCTMs) with magnetically interacting ions have been proposed as components for information-processing devices and storage units. For any practical application of MCTMs as magnetic units, it is crucial to characterize their magnetic behavior, and in particular, the isotropic magnetic exchange coupling, , between its magnetic centers. Due to the large size of typical MCTMs, density functional theory is the only practical electronic structure method for evaluating the coupling. Here, we assess the accuracy of different density functional approximations for predicting the magnetic couplings of eight dinuclear transition-metal complexes, including five dimanganese, two dicopper, and one divanadium with known reliable experimental couplings spanning from ferromagnetic to strong antiferromagnetic. The density functionals considered include global hybrid functionals which mix semilocal density functional approximations and exact exchange with a fixed admixing parameter, six local hybrid functionals where the admixing parameters are extended to be spatially dependent, the SCAN and SCAN meta-generalized gradient approximations (GGAs), and two widely used GGAs. We found that global hybrids tested in this work have a tendency to over-correct the error in magnetic coupling parameters from the Perdew-Burke-Ernzerhof (PBE) GGA as seen for manganese complexes. The performance of local hybrid density functionals shows no improvement in terms of bias and is scattered without a clear trend, suggesting that more efforts are needed for the extension from global to local hybrid density functionals for this particular property. The SCAN and SCAN -GGAs are found to perform as well as benchmark global hybrids on most tested complexes. We further analyze the charge density redistribution of -GGAs as well as global and local hybrid density functionals with respect to that of PBE, in connection to the self-interaction error or delocalization error.
具有磁相互作用离子的多中心过渡金属配合物（MCTMs）已被提议作为信息处理设备和存储单元的组件。对于MCTMs作为磁性单元的任何实际应用，表征其磁行为至关重要，尤其是其磁中心之间的各向同性磁交换耦合。由于典型MCTMs的尺寸较大，密度泛函理论是评估耦合的唯一实用电子结构方法。在此，我们评估了不同密度泛函近似方法预测八种双核过渡金属配合物磁耦合的准确性，其中包括五个二锰、两个二铜和一个二钒配合物，其已知可靠的实验耦合范围从铁磁到强反铁磁。所考虑的密度泛函包括将半局部密度泛函近似与精确交换以固定混合参数混合的全局杂化泛函、六个混合参数扩展为空间相关的局部杂化泛函、SCAN和SCAN元广义梯度近似（GGA）以及两种广泛使用的GGA。我们发现，在这项工作中测试的全局杂化泛函倾向于过度校正来自Perdew-Burke-Ernzerhof（PBE）GGA的磁耦合参数误差，这在锰配合物中可以看到。局部杂化密度泛函的性能在偏差方面没有改善，并且分散且没有明显趋势，这表明对于从全局到局部杂化密度泛函的这种特定性质的扩展需要更多努力。发现SCAN和SCAN -GGA在大多数测试配合物上的表现与基准全局杂化泛函一样好。我们进一步分析了-GGA以及全局和局部杂化密度泛函相对于PBE的电荷密度重新分布，这与自相互作用误差或离域误差有关。
