标题： 一维过渡金属氧化物链作为从头计算的挑战性模型 显示英文标题

标题： 1D Transition Metal Oxide Chains as a Challenging Model for Ab Initio Calculations

摘要： 提供高度简化的强关联电子系统模型，这些模型挑战了{\it 从头算}的计算能力，可以作为改进这些方法的宝贵试验平台。 在这项研究中，我们利用密度泛函理论（DFT）、DFT+$U$和耦合簇单双激发（CCSD）计算，全面研究了一维过渡金属单氧化物链（VO、CrO、MnO、FeO、CoO 和 NiO）的结构、磁性和电子性质。 对于 DFT+$U$，我们使用线性响应理论来确定Hubbard $U$参数。 在除 MnO 之外的所有研究系统中，由于与 d 轨道相关的电子自由度导致存在多个局域极小值，这给 DFT、DFT+U 和 Hartree-Fock 方法在从头算计算中找到全局最小值带来了显著挑战。 我们的结果显示，对于所有链状结构，除了使用 DFT+$U$和 PBE 时的 CrO，反铁磁（AFM）状态在能量上更为有利。 我们分析了电子能带结构，发现虽然 PBE 近似通常预测铁磁（FM）态为金属或半金属基态，但 DFT+$U$方法成功打开了能隙，正确地预测了所有情况下的绝缘行为。 此外，我们使用 DFT+$U$和 CCSD 比较了 CrO、MnO、FeO、CoO 和 NiO 中 AFM 和 FM 态之间的能量差异。 我们的研究结果表明，在某些情况下，CCSD 预测的能量差异比 DFT+$U$更大，这表明通过线性响应理论获得的Hubbard$U$参数在用于计算不同磁态之间的能量差异时可能会被高估。 对于CrO，CCSD 预测的是反铁磁（AFM）基态，这与 DFT+$U$和 PBE 方法的预测相反。 显示英文摘要

摘要： Providing highly simplified models of strongly correlated electronic systems that challenge {\it ab initio} calculations can serve as a valuable testing ground to improve these methods. In this study, we present a comprehensive study of the structural, magnetic, and electronic properties of one-dimensional transition metal mono-oxide chains (VO, CrO, MnO, FeO, CoO, and NiO) using density functional theory (DFT), DFT+$U$, and coupled-cluster singles and doubles (CCSD) calculations. The Hubbard $U$ parameter for DFT+$U$ is determined using the linear response theory. In all systems studied except MnO, the presence of multiple local minima -- primarily due to the electronic degrees of freedom associated with the d-orbitals -- leads to significant challenges for DFT, DFT+U, and Hartree-Fock methods in finding the global minimum in ab initio calculations. Our results indicate that the antiferromagnetic (AFM) state is energetically favored for all chains, except CrO, when using DFT+$U$ and PBE. We analyze the electronic band structures and find that while the PBE approximation often predicts metallic or half-metallic ground states for the ferromagnetic (FM) state, DFT+$U$ approach successfully opens band gaps, correctly predicting insulating behavior in all cases. Furthermore, we compared the energy differences between the AFM and FM states using DFT+$U$ and CCSD for CrO, MnO, FeO, CoO and NiO. Our findings indicate that CCSD predicts larger energy differences in some cases compared to DFT+$U$, suggesting that the Hubbard $U$ parameter obtained through linear response theory may be overestimated when used to calculate energy differences between different magnetic states. For CrO, CCSD predicts an AFM ground state, in contrast to the predictions from DFT+$U$ and PBE methods.