为什么在分子内电荷转移激发计算中,长距离纠正密度函数的距离分离参数的最佳调整方法失败?
Han-Seok Bae1, Dae-Hwan Ahn1, Jong-Won Song1
1Department of Chemistry Education, Daegu University, Gyeongsan-si 113-8656, Republic of Korea.
Molecules (Basel, Switzerland)
|September 28, 2024
概括
在结合系统中,电荷转移 (CT) 激发能随着更强的电子吸收组而下降. 分区密度函数理论 (DFT) 的最佳调整 (OT) 准确地预测了分子间CT,但不是分子内CT激发能.
科学领域:
- 计算化学计算化学
- 量子化学 是一个量子化学.
- 频谱学是一种光谱学.
背景情况:
- 了解电荷转移 (CT) 过程在联系统中至关重要.
- 精确计算CT激发能量需要适当的理论方法.
- 替代物效应和距离对CT的影响是研究的一个关键领域.
研究的目的:
- 调查电子提取/捐赠功能组和电荷转移距离对分子内和分子间CT激发能量的影响.
- 评估各种计算方法的性能,包括最佳调整 (OT) 长距离校正 (LC) 密度函数理论 (DFT),用于预测CT刺激能量.
- 阐明不同理论方法对内部和分子间CT现象的准确性的因素.
主要方法:
- 对结合碳链及其键复合体的内部和分子间CT激发能量的计算.
- 采用了诸如单元和双元的运动方程合集群 (EOM-CCSD),时间依赖的Hartree-Fock (TD-HF) 和各种DFT函数 (BLYP,B3LYP,LC-DFT) 等方法.
- 应用OT-LC-DFT与基于库普曼定理的优化调节范围分离参数 (μ).
主要成果:
- 随着终端功能组 (X) 的电子吸收强度的增加,内部和分子间CT激发能量通常都会减少.
- 取电子组对分子内CT激发能量的影响很小 (≤0.5 eV).
- 与标准LC-DFT相比,OT-LC-DFT准确地预测了分子间CT激发能量,但在分子内CT激发能量方面表现不佳.
结论:
- 最优的调方法对于准确预测分子内CT激发能量是不有效的.
- 分子间CT激发能受到激发性结合能的影响,随着距离的变化表现出不对称的行为,并且不那么依赖范围分离参数.
- 内分子CT激发能量受到轨道放松能量的显著影响,该能量对范围分离参数的选择敏感,使OT方法不适合其准确的预测.
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