Mechanism of Spin-Exchange Internal Conversion: Practical Proxies for Diabatic and Nonadiabatic Couplings
Mechanism of Spin-Exchange Internal Conversion: Practical Proxies for Diabatic and Nonadiabatic Couplings
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DOI：
10.1021/acs.jctc.8b00923
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发表时间：
2019-03-01
影响因子：
5.5
通讯作者：
Barbatti, Mario
中科院分区：
文献类型：
--
作者：
Bai, Shuming;Barbatti, Mario
自旋交换内转换（SEIC）是一类具有单线态裂变和三线态聚变作为特殊情况的反应。基于电荷转移（CT）介导的机制和分析推导模型哈密顿量，我们提出了代理估计耦合强度在一般SEIC反应的非绝热和绝热图片。在非绝热图像中，我们证明了耦合强度和分子轨道重叠之间存在双线性关系，这为预测非绝热耦合提供了一种实用的方法。在绝热图中，我们证明了非绝热耦合可以用波函数CT系数的简单函数来近似。这些方法通过研究单线态氧光敏化来验证，其中（1）Delta（g）和（1）Sigma（g）氧状态都可以通过三重态熔合反应竞争性地产生。在反应过程中，CT介导的机制、双分子复合物的空间因素和氧分子的电子结构之间的相互作用解释了沿着沿着特定入射方向与（1）σ（g）态的奇怪的小耦合。从非绝热和绝热图片的结果提供了一个全面的理解的反应机制，适用于一般的SEIC问题。
Spin-exchange internal conversion (SEIC) is a general class of reactions having singlet fission and triplet fusion as particular cases. Based on a charge transfer (CT) mediated mechanism and analytical derivation with a model Hamiltonian, we propose proxies for estimating the coupling strength in both diabatic and adiabatic pictures for general SEIC reactions. In the diabatic picture, we demonstrated the existence of a bilinear relationship between the coupling strength and molecular orbital overlap, which provides a practical way to predict diabatic couplings. In the adiabatic picture, we showed that nonadiabatic couplings can be approximated by simple functions of the wave function CT coefficients. These approaches were verified through the investigation of singlet oxygen photosensitization, where both (1)Delta(g) and (1)Sigma(g) oxygen states can be competitively generated by a triplet fusion reaction. The interplay between the CT-mediated mechanism, the spatial factors of the bimolecular complex, and the electronic structure of the oxygen molecule during the reaction explains the curiously small coupling to the (1)Sigma(g) state along specific incidence directions. The results from both the diabatic and adiabatic pictures provide a comprehensive understanding of the reaction mechanism, which applies to general SEIC problems.