无需单激发即可获得可靠偶极矩：轨道旋转与动态相关的作用
Toward Reliable Dipole Moments without Single Excitations: The Role of Orbital Rotations and Dynamical Correlation
AI总结：
本文系统评估 pCCD 及 pCCD-LCC 在不同轨道、密度矩阵和基组下的电子偶极矩预测，强调轨道弛豫作用并指出线性化校正对多重键体系的局限。
摘要：
偶极矩是一项关键分子性质，与分子体系的键极性和整体电子结构相关。为此，由体系电子密度产生的电子偶极矩常被用于评估新型电子结构方法的准确性和可靠性。本工作分析了采用 pair coupled cluster doubles（pCCD）拟设及其 linearized coupled cluster（pCCD-LCC）校正，并使用正则 Hartree–Fock 和 pCCD 优化（定域）轨道基组计算得到的电子偶极矩。研究利用弛豫和非弛豫密度矩阵以及不同大小的基组，对照实验值和 CCSD(T) 参考值评估了基于 pCCD 的偶极矩准确性。测试集包含具有多种成键模式和电子结构的分子，使基于 pCCD 的方法面对广泛的电子相关效应。此外，我们还考察了若干模型配合物的 pCCD-in-DFT 偶极矩表现。最后，本工作表明 pCCD 模型中轨道弛豫的重要性，并揭示了线性化耦合簇校正在预测多重键体系电子偶极矩方面的局限。最重要的是，带 linearized CCD 校正的 pCCD 能够重现单键分子的偶极矩面，其结果可与多参考方法相媲美。
英文摘要：
The dipole moment is a crucial molecular property linked to a molecular system's bond polarity and overall electronic structure. To that end, the electronic dipole moment, which results from the electron density of a system, is often used to assess the accuracy and reliability of new electronic structure methods. This work analyses electronic dipole moments computed with the pair coupled cluster doubles (pCCD) ansatz and its linearized coupled cluster (pCCD-LCC) corrections using the canonical Hartree--Fock and pCCD-optimized (localized) orbital bases. The accuracy of pCCD-based dipole moments is assessed against experimental and CCSD(T) reference values using relaxed and unrelaxed density matrices and different basis set sizes. Our test set comprises molecules of various bonding patterns and electronic structures, exposing pCCD-based methods to a wide range of electron correlation effects. Additionally, we investigate the performance of pCCD-in-DFT dipole moments of some model complexes. Finally, our work indicates the importance of orbital relaxation in the pCCD model and shows the limitations of the linearized couple cluster corrections in predicting electronic dipole moments of multiple-bonded systems. Most importantly, pCCD with a linearized CCD correction can reproduce the dipole moment surfaces in singly-bonded molecules, which are comparable to the multi-reference ones.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
