Chakraborty Rahul, Boguslawski Katharina, Tecmer Paweł
Institute of Physics, Faculty of Physics, Astronomy, and Informatics, Nicolaus Copernicus University in Toruń, Grudziadzka 5, 87-100 Toruń, Poland.
Phys Chem Chem Phys. 2023 Sep 27;25(37):25377-25388. doi: 10.1039/d3cp02502k.
Quantum embedding methods have recently been significantly developed to model large molecular structures. This work proposes a novel wave function theory in a density functional theory (WTF-in-DFT) embedding scheme based on pair-coupled cluster doubles (pCCD)-type methods. While pCCD can reliably describe strongly-correlated systems with mean-field-like computational cost, the large extent of the dynamic correlation can be accounted for by (linearized) coupled-cluster corrections on top of the pCCD wave function. Here we focus on the linearized coupled-cluster singles and doubles (LCCSD) ansatz for electronic ground states and its extension to excited states within the equation of motion (EOM) formalism. We test our EOM-pCCD-LCCSD-in-DFT approach for the vertical excitation energies of the hydrogen-bonded water-ammonia complex, micro-solvated thymine, and uranyl tetrahalides (UOX, X = F, Cl, Br). Furthermore, we assess the quality of the embedding potential using an orbital entanglement and correlation analysis. The approximate embedding models successfully capture changes in the excitation energies going from bare fragments to supramolecular structures and represent a promising computational method for excited states in large molecular systems.
量子嵌入方法最近得到了显著发展，用于对大分子结构进行建模。这项工作提出了一种基于对耦合簇双激发（pCCD）型方法的密度泛函理论（DFT）嵌入方案中的新型波函数理论（WTF-in-DFT）。虽然pCCD能够以类似平均场的计算成本可靠地描述强关联系统，但动态关联的很大一部分可以通过在pCCD波函数之上的（线性化）耦合簇校正来考虑。在这里，我们专注于电子基态的线性化耦合簇单激发和双激发（LCCSD）假设及其在运动方程（EOM）形式体系中向激发态的扩展。我们测试了我们的EOM-pCCD-LCCSD-in-DFT方法对氢键合水 - 氨络合物、微溶剂化胸腺嘧啶和四卤化铀酰（UOX，X = F、Cl、Br）的垂直激发能。此外，我们使用轨道纠缠和关联分析来评估嵌入势的质量。近似嵌入模型成功捕捉了从裸片段到超分子结构时激发能的变化，并代表了一种用于大分子系统激发态的有前途的计算方法。
