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标题: 明态（S bright state）暗态（S dark state）、detachment/attachment density 的问题 [打印本页]

作者
Author: 18522780016 时间: 2018-1-12 05:37
标题: 明态（S bright state）暗态（S dark state）、detachment/attachment density 的问题
各位大神以及sob老师好，小弟是做有机合成的，对计算刚刚接触，看到一篇文献的supportinginformation中提到明态（S bright state）暗态（S dark state）以及detachment/attachment density analysis，对这三个概念不太理解其含义，也试图搜索过，并没有找到答案，还请大神们赐教。不胜感激，小弟CSC德国读博，如有意愿的也可联系，提供无偿帮助
关于下图和文献内容小弟有以下几个问题：
1. 明态（S bright state）和暗态（S dark state）分别的含义是什么，明态是否就是指S1（第一单重激发态）？
2. 作者在利用“detachment/attachment density analysis”对“hole (A) and electron (B) wavefunctions”进行近似，这个“detachment/attachment density analysis”和“hole (A) and electron (B) wavefunctions”又指的是什么，和HOMO\LUMO轨道能级图又有啥关系？
以下是问下原文和图：
For consistent and accurate description of the many different states involved in the singlet fission process, we have employed several methods, all rooted in density functional theory (DFT), to help us identify key intermediate states. More specifically, we use regular DFT calculations for the S0 and T1 states, linear response time-dependent (TD) DFT53 for the Sbright state, and constrained DFT approach54 for the T1T1 state. All calculations are done with the package QChem at the level of B3LYP/6-31G*. Complete results for the model system BTDO2 are provided. All molecular geometries used in calculations are fully optimized, and all energy values are presented as calculated without adjustment. Because most implementations of TDDFT do not provide access to doubly excited states,56 we are unable to calculate the S dark state.

Scheme S1. Initial and Final Electronic States. After optical excitation (hν) the singlet
charge transfer exciton (S bright|CT) is formed. The hole (A) and electron (B)
wavefunctions are approximated with detachment/attachment density analysis. (C) The
iSF process results in conversion of the Sbright state (1.52 eV) to a pair of localized triplets
(2 T1) with a total energy of 1.43 eV. The detrimental internal conversion (IC) pathway,
which competes with iSF on a sub-picosecond timescale in some systems, is also
displayed. We note that the states displayed here are the initial and final electronic states
in the iSF process. The transition from singlet exciton to triplet pair does not occur
directly; a more detailed discussion of the iSF mechanism is included in the SI section.

作者
Author: kyuu 时间: 2018-1-12 07:34
从图C里看的是 dark是虚态，bright是确定态

作者
Author: 函数与激情 时间: 2018-1-12 11:06
本帖最后由函数与激情于 2018-1-12 11:12 编辑

仅限我的理解，明态指的是光打到的激发态，一般是pai-pai态居多，暗态与明态相反，一般是n-pai态居多。比如光的能量打到S2，对应于实验的光谱吸收，那么S2就是光谱明态，S1就是暗态。

作者
Author: sobereva 时间: 2018-1-12 12:52
明态就是实验可观测的态，暗态是实验观测不到的态。理论计算时根据振子强度是否接近于0也可以一定程度上区分
hole和electron可以用Multiwfn的主功能18的子功能1计算，手册4.18.1节有例子，3.21.1.1节有理论介绍。如果某对电子态跃迁恰对应某对轨道的跃迁，则hole,electron分布也可以通过计算相应两个轨道对应的密度得到

作者
Author: 18522780016 时间: 2018-1-12 17:52

sobereva 发表于 2018-1-12 12:52
明态就是实验可观测的态，暗态是实验观测不到的态。理论计算时根据振子强度是否接近于0也可以一定程度上区 ...

感谢sob老师的解答，受教了

作者
Author: 18522780016 时间: 2018-1-12 17:54

函数与激情发表于 2018-1-12 11:06
仅限我的理解，明态指的是光打到的激发态，一般是pai-pai态居多，暗态与明态相反，一般是n-pai态居多。比如 ...

感谢回答

作者
Author: 18522780016 时间: 2018-1-12 17:57

kyuu 发表于 2018-1-12 07:34
从图C里看的是 dark是虚态，bright是确定态

感谢回答

作者
Author: 18522780016 时间: 2018-1-12 20:50

sobereva 发表于 2018-1-12 12:52
明态就是实验可观测的态，暗态是实验观测不到的态。理论计算时根据振子强度是否接近于0也可以一定程度上区 ...

sob老师，我还有个问题，原文中提到“As shown in Scheme S1, the electron density is more
localized on both left and right TDO units while the hole density is more delocalized over the
whole molecule. This suggests a weak charge transfer mixing in the S bright state”，如何理解从“electron density”和“hole density”途中就能看出有“a weak charge transfer mixing in the S bright state”，感谢

作者
Author: sobereva 时间: 2018-1-14 22:53

18522780016 发表于 2018-1-12 20:50
sob老师，我还有个问题，原文中提到“As shown in Scheme S1, the electron density is more
localized ...

hole分布于整体，electron分布于两侧，显然电子从hole向electron描述的分布区域来跃迁，就对应一定程度的电子从体系中央向两边移动

作者
Author: 18522780016 时间: 2018-1-18 03:54

sobereva 发表于 2018-1-14 22:53
hole分布于整体，electron分布于两侧，显然电子从hole向electron描述的分布区域来跃迁，就对应一定程度 ...

感谢老师

作者
Author: xiaoma0417 时间: 2018-7-18 18:59
您好，可否分享这篇文献

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