Sánchez-Mansilla A, Sousa C, Kathir R K, Broer R, Straatsma T P, de Graaf C
Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Tarragona, Spain.
Departament de Ciència de Materials i Química Física and Institut de Química Teòrica i Computacional, Universitat de Barcelona, Spain.
Phys Chem Chem Phys. 2022 May 18;24(19):11931-11944. doi: 10.1039/d2cp00772j.
Two different approaches have been implemented to include the effect of dynamic electron correlation in the Non-Orthogonal Configuration Interaction for Fragments (NOCI-F) method. The first is based on shifting the diagonal matrix elements of the NOCI matrix, while the second incorporates the dynamic correlation explicitly in the fragment wave functions used to construct the many-electron basis functions of the NOCI. The two approaches are illustrated for the calculation of the electronic coupling relevant in singlet fission and the coupling of spin moments in organic radicals. Comparison of the calculated diabatic couplings, the NOCI energies and wave functions shows that dynamic electron correlation is not only efficiently but also effectively incorporated by the shifting approach and can largely affect the coupling between electronic states. Also, it brings the NOCI coupling of the spin moments in close agreement with benchmark calculations.
为了在片段非正交组态相互作用（NOCI-F）方法中纳入动态电子关联效应，已经实施了两种不同的方法。第一种方法基于移动NOCI矩阵的对角矩阵元，而第二种方法则在用于构建NOCI多电子基函数的片段波函数中明确纳入动态关联。通过计算单线态裂变中相关的电子耦合以及有机自由基中自旋矩的耦合来说明这两种方法。对计算得到的非绝热耦合、NOCI能量和波函数的比较表明，动态电子关联不仅能被移动方法有效地纳入，而且能显著影响电子态之间的耦合。此外，它使得自旋矩的NOCI耦合与基准计算结果非常吻合。
