Wavelength‐decomposition‐based embedded cluster density approximation for systems with nonlocal electron correlation
Wavelength‐decomposition‐based embedded cluster density approximation for systems with nonlocal electron correlation
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DOI：
10.1002/qua.26347
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发表时间：
2020-07
影响因子：
2.2
通讯作者：
Chen Huang
中科院分区：
文献类型：
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作者：
Chen Huang
局域相关方法依赖于电子相关是近视的假设。在这项工作中，我们开发了一种方法来减轻这种假设。通过计算几个一维模型系统中的随机相位近似（RPA）相关能，证明了这种新方法。该方法首先根据Langreth和Perdew提出的电子关联的波长分解，将RPA关联能近似分解为近视和远视分量。RPA相关能量的短波长（SW）分量被认为是近视的，RPA相关能量的长波长（LW）分量被认为是远视的。SW RPA的相关能量计算使用最近开发的本地相关方法：嵌入集群密度近似（ECDA）。LW RPA相关能是基于系统的Kohn-Sham轨道全局计算的。这种新方法被称为λ-ECDA，其中λ表示波长分解。λ-ECDA的性能在一维模型系统上进行了研究：H24链，其中RPA相关能是高度非局域的。在这个模型系统中，一个软化的库仑相互作用被用来描述电子-电子和电子-离子相互作用，并将稍强的核电荷（1.2e）分配给赝H原子。当团簇相当大时，λ-ECDA预测的键伸缩能、RPA相关势和Kohn-Sham本征值与基准值吻合得很好。我们发现，LW RPA相关能量是获得准确预测的RPA相关潜力的关键，即使LW RPA相关能量只占总RPA相关能量的百分之几。
Local correlation methods rely on the assumption that electron correlation is nearsighted. In this work, we develop a method to alleviate this assumption. This new method is demonstrated by calculating the random phase approximation (RPA) correlation energies in several one‐dimensional model systems. In this new method, the first step is to approximately decompose the RPA correlation energy to the nearsighted and farsighted components based on the wavelength decomposition of electron correlation developed by Langreth and Perdew. The short‐wavelength (SW) component of the RPA correlation energy is then considered to be nearsighted, and the long‐wavelength (LW) component of the RPA correlation energy is considered to be farsighted. The SW RPA correlation energy is calculated using a recently developed local correlation method: the embedded cluster density approximation (ECDA). The LW RPA correlation energy is calculated globally based on the system's Kohn‐Sham orbitals. This new method is termedλ‐ECDA, whereλindicates the wavelength decomposition. The performance ofλ‐ECDA is examined on a one‐dimensional model system: a H24chain, in which the RPA correlation energy is highly nonlocal. In this model system, a softened Coulomb interaction is used to describe the electron‐electron and electron‐ion interactions, and slightly stronger nuclear charges (1.2e) are assigned to the pseudo‐H atoms. Bond stretching energies, RPA correlation potentials, and Kohn‐Sham eigenvalues predicted byλ‐ECDA are in good agreement with the benchmarks when the clusters are made reasonably large. We find that the LW RPA correlation energy is critical for obtaining accurate prediction of the RPA correlation potential, even though the LW RPA correlation energy contributes to only a few percent of the total RPA correlation energy.