Imposing correct jellium response is key to predict the density response by orbital-free DFT
Imposing correct jellium response is key to predict the density response by orbital-free DFT
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DOI：
10.1103/physrevb.108.235168
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发表时间：
2023-04
影响因子：
3.7
通讯作者：
Z. Moldabekov;Xuecheng Shao;M. Pavanello;J. Vorberger;Frank Graziani;T. Dornheim
中科院分区：
文献类型：
--
作者：
Z. Moldabekov;Xuecheng Shao;M. Pavanello;J. Vorberger;Frank Graziani;T. Dornheim
无轨道密度泛函理论（OF - DFT）是一种在计算上非常有效的工具，可用于对从室温材料到温稠密物质等系统的电子结构进行建模。其准确性关键取决于所采用的动能（KE）密度泛函，该泛函必须作为外部输入提供。在这项工作中，我们考虑了几种非局域和拉普拉斯层级的KE泛函，并使用外部简谐微扰来计算线性及超线性响应区域中T = 0 K时的静态密度响应。我们测试了在均匀密度极限下精确条件的满足情况，以及近似的KE泛函如何针对采用精确KE的科恩 - 沈吕九（Kohn - Sham）DFT参考来重现实际材料（例如，铝和硅）的密度响应。结果表明，几种泛函在均匀电子气（UEG）极限下违反精确条件。我们发现UEG极限下KE泛函的准确性与强非均匀情况之间存在很强的相关性。这从经验上证明了对均匀密度施加UEG响应极限的重要性，并验证了在非局域泛函的核公式中使用林德哈德（Lindhard）函数。通过对具有面心立方（fcc）晶格的块状铝（Al）以及具有fcc晶格、体心立方（bcc）晶格和半导体金刚石（cd）态的硅（Si）进行的额外计算，进一步证实了这一结论。对fcc Al以及fcc和bcc Si数据的分析与针对UEG得出的结论密切相符，这使我们能够将结论扩展到受离子诱导的密度不均匀性影响的实际系统。
Orbital-free density functional theory (OF-DFT) constitutes a computationally highly effective tool for modeling electronic structures of systems ranging from room-temperature materials to warm dense matter. Its accuracy critically depends on the employed kinetic energy (KE) density functional, which has to be supplied as an external input. In this work we consider several nonlocal and Laplacian-level KE functionals and use an external harmonic perturbation to compute the static density response at T=0 K in the linear and beyond linear response regimes. We test for the satisfaction of exact conditions in the limit of uniform densities and for how approximate KE functionals reproduce the density response of realistic materials (e.g., Al and Si) against the Kohn-Sham DFT reference which employs the exact KE. The results illustrate that several functionals violate exact conditions in the UEG limit. We find a strong correlation between the accuracy of the KE functionals in the UEG limit and in the strongly inhomogeneous case. This empirically demonstrates the importance of imposing the limit of UEG response for uniform densities and validates the use of the Lindhard function in the formulation of kernels for nonlocal functionals. This conclusion is substantiated by additional calculations for bulk Aluminum (Al) with a face-centered cubic (fcc) lattice and Silicon (Si) with an fcc lattice, body-centered cubic (bcc) lattice, and semiconducting crystal diamond (cd) state. The analysis of fcc Al, and fcc as well as bcc Si data follows closely the conclusions drawn for the UEG, allowing us to extend our conclusions to realistic systems that are subject to density inhomogeneities induced by ions.