Computer Network Information Center, Chinese Academy of Sciences, Beijing 100190, China.
Phys Chem Chem Phys. 2020 Mar 4;22(9):4957-4966. doi: 10.1039/c9cp06417f.
We analyzed the near-degenerate states of the firefly dioxetanone anion (FDO-) and its prototypes, especially in the biradical region, using multi-configurational approaches. The importance of utilizing full valence active spaces by means of density-matrix renormalization group self-consistent field (DMRG-SCF) calculations was described. Our results revealed that the neglect of some valence orbitals can affect the quantitative accuracy in later multi-reference calculations or the qualitative conclusion when optimizing conical intersections. Using all of the relevant valence orbitals of FDO-, we confirmed that there were two conical intersections, as reported in previous work, and that the intersecting states were changed when the active space was enlarged. Beyond these, we found that there were strong interactions between states in the biradical regions, in which the changes in entanglements can be used to visualize the interacting state evolution.
我们使用多组态方法分析了萤火虫二氧戊环阴离子（FDO-）及其原型的近简并态，特别是在双自由基区域。文中描述了通过密度矩阵重整化群自洽场（DMRG-SCF）计算利用全价活性空间的重要性。我们的结果表明，忽略一些价轨道会影响后续多参考计算的定量精度，或者在优化锥形交叉时影响定性结论。使用 FDO-的所有相关价轨道，我们证实了正如之前的工作所报道的那样存在两个锥形交叉，并且当活性空间扩大时，交叉状态发生了变化。除此之外，我们发现双自由基区域中各态之间存在强烈相互作用，其中纠缠的变化可用于可视化相互作用态的演化。
