We describe the ground- and excited-state electronic structure of bulk MnO and NiO, two prototypical correlated electron materials, using coupled cluster theory with single and double excitations (CCSD). As a corollary, this work also reports the first implementation of unrestricted periodic ab initio equation-of motion CCSD. Starting from a Hartree-Fock reference, we find fundamental gaps of 3.46 eV and 4.83 eV for MnO and NiO respectively for the 16 unit supercell, slightly overestimated compared to experiment, although finite-size scaling suggests that the gap is more severely overestimated in the thermodynamic limit. From the character of the correlated electronic bands we find both MnO and NiO to lie in the intermediate Mott/charge-transfer insulator regime, although NiO appears as a charge transfer insulator when only the fundamental gap is considered. While the lowest quasiparticle excitations are of metal 3$d$ and O 2$p$ character in most of the Brillouin zone, near the $\Gamma$ point, the lowest conduction band quasiparticles are of $s$ character. Our study supports the potential of coupled cluster theory to provide high level many-body insights into correlated solids.

中文翻译：

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耦合簇理论的块状氧化锰和氧化镍电子结构

我们使用单和双激发（CCSD）耦合簇理论描述了本体MnO和NiO这两种原型相关的电子材料的基态和激发态电子结构。因此，这项工作还报告了无限制周期性从头算起的运动方程CCSD的首次实现。从Hartree-Fock参考资料开始，我们发现16个单元超级电池的MnO和NiO的基本间隙分别为3.46 eV和4.83 eV，与实验相比略有高估，尽管有限尺寸的缩放表明该间隙在模型中被严重高估了。热力学极限。根据相关电子带的特性，我们发现MnO和NiO都位于中间的Mott /电荷转移绝缘体体系中，尽管仅考虑基本间隙，但NiO似乎是电荷转移绝缘体。最低的准粒子激发是金属3$d$ 和O 2$p$ 大部分布里渊区的角色， $\Gamma$ 点，最低的导带准粒子是 $s$字符。我们的研究支持耦合聚类理论为相关固体提供高级多体见解的潜力。