Department of Chemistry, University of Michigan, 930N. University Avenue, Ann Arbor 48109, Michigan, United States.
J Phys Chem A. 2021 Feb 25;125(7):1598-1609. doi: 10.1021/acs.jpca.0c07624. Epub 2021 Feb 10.
An efficacious approximation to full configuration interaction (FCI) is adapted to calculate singlet-triplet gaps for transition-metal complexes. This strategy, incremental FCI (iFCI), uses a many-body expansion to systematically add correlation to a simple reference wave function and therefore achieves greatly reduced computational costs compared to FCI. iFCI through the 3-body expansion is demonstrated on four model transition-metal complexes involving the metals Zn, V, and Cu. Screening techniques to increase the computational efficiency of iFCI are proposed and tested, showing reduction in the number of 3-body terms by more than 90% with controlled errors. The largest complex treated herein by iFCI has 142 valence electrons, all of which are correlated among the full set of 444 active orbitals. Computed spin gaps approach experimental results for the four complexes, though room for improvement remains.
一种有效的全组态相互作用（FCI）逼近方法被用于计算过渡金属配合物的单重态-三重态能隙。这种策略，增量全组态相互作用（iFCI），使用多体展开式来系统地向简单参考波函数添加关联，因此与 FCI 相比大大降低了计算成本。在涉及 Zn、V 和 Cu 等金属的四个模型过渡金属配合物上展示了通过 3 体展开式的 iFCI。提出并测试了提高 iFCI 计算效率的筛选技术，表明 3 体项的数量减少了 90%以上，且误差可控。本文中通过 iFCI 处理的最大配合物具有 142 个价电子，它们全部在 444 个全活性轨道的完整集合中相互关联。计算出的自旋能隙接近四个配合物的实验结果，但仍有改进的空间。
