Sustainable hydrogen production is one of the most important topics in modern energy economics. Of technological relevance are, for example, electrochemical and thermal splitting of water. For such processes anode materials with a variable concentration of oxygen defects are required. Herein, the oxygen defect thermochemistry of a possible anode material, the perovskite CaMnO₃, is investigated theoretically. The aim of this work is to identify reliable quantum chemical methods for the calculation of oxygen defect formation enthalpies and entropies, including configuration entropy, which is usually neglected. All possible defect configurations in a supercell are computed to obtain the configuration entropy using Boltzmann statistics. Various generalized gradient approximation (GGA), meta-GGA, and hybrid functionals as implemented in the solid-state programs CRYSTAL and VASP are evaluated for the calculation of structure parameters, electronic and magnetic properties, and reaction energies of CaMnO₃. The global hybrid functional PW1PW gives the most accurate overall description of CaMnO₃ and is therefore recommended for future theoretical studies of more efficient water-splitting catalysts based on calcium manganate.

中文翻译：

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CaMnO3 的氧缺陷形成热力学：近距离观察

可持续制氢是现代能源经济学中最重要的课题之一。与技术相关的是，例如，水的电化学和热分解。对于此类工艺，需要具有可变氧缺陷浓度的阳极材料。在此，可能的阳极材料钙钛矿 CaMnO _{3的氧缺陷热化学}, 进行了理论上的研究。这项工作的目的是确定可靠的量子化学方法来计算氧缺陷形成的焓和熵，包括通常被忽略的构型熵。使用玻尔兹曼统计计算超晶胞中所有可能的缺陷配置以获得配置熵。对在固态程序 CRYSTAL 和 VASP 中实施的各种广义梯度近似 (GGA)、元 GGA 和混合泛函进行了评估，以计算 CaMnO ₃的结构参数、电子和磁性特性以及反应能。_{全局混合泛函 PW1PW 给出了 CaMnO 3}最准确的整体描述因此推荐用于未来基于锰酸钙的更有效的水分解催化剂的理论研究。