Projection-based embedding offers a simple framework for embedding correlated wavefunction methods in density functional theory. Partitioning between the correlated wavefunction and density functional subsystems is performed in the space of localized molecular orbitals. However, during a large geometry change—such as a chemical reaction—the nature of these localized molecular orbitals, as well as their partitioning into the two subsystems, can change dramatically. This can lead to unphysical cusps and even discontinuities in the potential energy surface. In this work, we present an even-handed framework for localized orbital partitioning that ensures consistent subsystems across a set of molecular geometries. We illustrate this problem and the even-handed solution with a simple example of an S_N2 reaction. Applications to a nitrogen umbrella flip in a cobalt-based CO₂ reduction catalyst and to the binding of CO to Cu clusters are presented. In both cases, we find that even-handed partitioning enables chemically accurate embedding with modestly sized embedded regions for systems in which previous partitioning strategies are problematic.

中文翻译：

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基于投影的嵌入中的偶手子系统选择

基于投影的嵌入为在密度泛函理论中嵌入相关波函数方法提供了一个简单的框架。相关波函数子系统和密度函数子系统之间的划分是在局部分子轨道的空间中进行的。但是，在较大的几何变化（例如化学反应）期间，这些局部分子轨道的性质以及将其划分为两个子系统的能力可能会发生巨大变化。这可能导致不自然的尖峰，甚至在势能表面不连续。在这项工作中，我们提出了一个用于局部轨道划分的平手框架，该框架可确保在一组分子几何结构上具有一致的子系统。我们用一个简单的S _N例子来说明这个问题和平手解决方案2反应。提出了在基于钴的CO ₂还原催化剂中的氮伞翻转中的应用以及在CO与Cu簇的结合中的应用。在这两种情况下，我们发现对于以前的分区策略有问题的系统，偶数分区可以实现化学上准确的嵌入，嵌入大小适中的区域。