Shil Suranjan
Manipal Centre for Natural Sciences, Manipal Academy of Higher Education, Manipal, Karnataka, India.
J Comput Chem. 2025 Jan 5;46(1):e27531. doi: 10.1002/jcc.27531.
The magnetic nature of nonalternant hydrocarbon (Azulene) bridged nitronyl nitroxide (AzNN) and imino-nitroxide (AzIN) diradicals are investigated with 38 different DFT functionals to find out a correct functional to predict the magnetic nature of these diradicals. The effect of Hartree-Fock exchange (HFX) in the hybrid functionals are investigated for the prediction of magnetic nature of the nonalternant hydrocarbon bridged diradicals. The utility of Borden and Davidson's proposal of disjoint and nondisjoint SOMOs for the prediction of magnetic nature of alternant hydrocarbon bridged diradicals is assessed for the nonalternant hydrocarbon based diradicals. The more affordable meta-GGA functionals was found to be outperforming the costlier hybrid and double-hybrid functionals in predicting the magnetic properties of nonalternant hydrocarbon-bridged diradicals. HFX significantly influences a functional's ability to predict a diradical's magnetic nature. Interestingly, Borden and Davidson's concept of disjoint and nondisjoint SOMOs, which is used to predict the magnetic behavior of alternant hydrocarbon diradicals, is reversed for nonalternant hydrocarbon-bridged diradicals. The difference in the magnetic nature of the two diradicals come from the canonical molecular orbitals of the diradicals, one has set of disjoint SOMOs and other has nondisjoint SOMOs.
使用38种不同的密度泛函理论（DFT）泛函研究了非交替烃（薁）桥连硝酰基氮氧自由基（AzNN）和亚氨基氮氧自由基（AzIN）双自由基的磁性，以找出能正确预测这些双自由基磁性的泛函。研究了混合泛函中哈特里-福克交换（HFX）对预测非交替烃桥连双自由基磁性的影响。评估了博登和戴维森提出的不相交和非不相交单占据分子轨道（SOMO）用于预测交替烃桥连双自由基磁性的方法在基于非交替烃的双自由基中的实用性。发现在预测非交替烃桥连双自由基的磁性性质时，成本较低的元广义梯度近似（meta-GGA）泛函比成本较高的混合泛函和双混合泛函表现更好。HFX显著影响泛函预测双自由基磁性性质的能力。有趣的是，用于预测交替烃双自由基磁性行为的博登和戴维森的不相交和非不相交SOMO概念在非交替烃桥连双自由基中发生了反转。这两种双自由基磁性性质的差异源于双自由基的正则分子轨道，一种具有一组不相交的SOMO，另一种具有非不相交的SOMO。
