Generalized Energy-Based Fragmentation Approach for the Electronic Emission Spectra of Large Systems
Generalized Energy-Based Fragmentation Approach for the Electronic Emission Spectra of Large Systems
复制标题
大型系统电子发射光谱的广义基于能量的碎片方法
DOI：
10.1021/acs.jctc.2c00911
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发表时间：
2022-11-18
影响因子：
5.5
通讯作者：
Li，Shuhua
中科院分区：
文献类型：
--
作者：
Du，Jiahui;Liao，Kang;Li，Shuhua
大体系的激发态几何构型优化、电子发射（荧光和磷光）光谱和激发态振动光谱是量子化学中的重大挑战。在这项工作中，我们开发了一个广义的基于能量的碎裂（GEBF）的方法来计算本地化ES结构和振动频率的大系统。在这种方法中，一个大系统的局域ES的ES能量导数（梯度或Hessians）可以通过组合相应的激活子系统（包括本地激发中心）的ES能量导数和非激活子系统的基态能量导数来获得。针对特定环境感知的状态分类和状态跟踪两个难点，本文采用了两种策略：首先，在状态分类方面，提出了一种改进的基于密度的空间聚类算法，该算法采用改进的过渡轨道投影（TOP）算法，其允许用活性物质的不同ES能量和能量导数计算整个系统的特定ES能量和能量导数，子系统此外，我们还采用TOP算法跟踪ES在其几何优化的含时密度泛函理论（TDDFT）水平。然后，GEBF方法被用来研究优化的ES几何结构或ES振动频率为两个典型的系统。我们的研究结果表明，具有成本效益的GEBF方法可以准确地再现TDDFT荧光光谱的胞嘧啶衍生物和实验的β-环糊精衍生物的磷光光谱。GEBF方法有望被常规应用于研究具有局部发色团的超大型系统的电子发射光谱。
The excited-state (ES) geometry optimization and electronic emission (fluorescence and phosphorescence) spectra and the ES vibrational spectra of large systems are great challenges in quantum chemistry. In this work, we develop a generalized energy-based fragmentation (GEBF) approach to compute the localized ES structures and vibrational frequencies of large systems. In this approach, the ES energy derivatives (gradients or Hessians) for a localized ES of a large system can be obtained by combining the ES energy derivatives of the corresponding active subsystems (including local excitation center) and the ground-state energy derivatives of inactive subsystems. Two strategies are adopted to overcome two difficulties from state-classification and state-tracking for treating specific ESs. First, for state-classification, we develop an improved density-based spatial clustering applied with noise algorithm with a modified transition orbital projection (TOP) algorithm, which allow a certain ES energy and energy derivatives of the whole system to be calculated with different ES energies and energy derivatives of active subsystems. Furthermore, we also employ the TOP algorithm for tracking the ESs in their geometry optimizations at the time-dependent density functional theory (TDDFT) level. Then, the GEBF approach is applied to investigate the optimized ES geometries or ES vibrational frequencies for two typical systems. Our results show that the cost-effective GEBF approach can accurately reproduce the TDDFT fluorescence spectra of the cytosine derivative and the experimental phosphorescence spectra of the β-cyclodextrin derivative. The GEBF approach is expected to be routinely applied to investigate the electronic emission spectra of very large systems with local chromophores.