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arXiv 2301.00535cond-mat.mtrl-sci
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r$^{2}$SCAN泛函在过渡金属氧化物中的性能

Performance of the r$^{2}$SCAN functional in transition metal oxides

S. Swathilakshmi, Reshma Devi, Gopalakrishnan Sai Gautam

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AI总结：

本研究评估了r$^2$SCAN泛函在过渡金属氧化物中的性能，确定了最优Hubbard U校正，验证了其可迁移性，发现该泛函计算效率更高且能较准确描述TMO基态性质。

摘要：

我们评估了最新开发的meta广义梯度近似（metaGGA）泛函——恢复型正则化强约束且适当归一化（r$^2$SCAN）在过渡金属氧化物（TMO）体系中的准确性和计算效率，并将其性能与SCAN进行对比。具体而言，我们将r$^2$SCAN计算得到的二元3d TMO的氧化焓、晶格参数、局域磁矩和带隙，与SCAN计算值及实验值进行基准测试。此外，我们基于实验氧化焓，确定了每种过渡金属（TM）所需的最优Hubbard U校正值，以提升r$^2$SCAN泛函的准确性，并通过与其他含过渡金属氧化物的实验性质对比，验证了U值的可迁移性。值得注意的是，对r$^2$SCAN引入U校正后，TMO的晶格参数、局域磁矩和带隙均有所增大，同时还改善了窄带隙TMO基态电子态的描述效果。r$^2$SCAN和r$^2$SCAN+U计算的氧化焓与SCAN和SCAN+U的定性趋势一致；与SCAN和SCAN+U相比，r$^2$SCAN和r$^2$SCAN+U分别预测出略大的晶格参数、更小的磁矩和更低的带隙。我们观察到，r$^2$SCAN(+U)所需的总计算时间（即所有离子步+电子步的耗时）低于SCAN(+U)。因此，r$^2$SCAN(+U)框架能够以优于SCAN(+U)的计算效率，对TMO的基态性质给出较为准确的描述。

英文摘要：

We assess the accuracy and computational efficiency of the recently developed meta-generalized gradient approximation (metaGGA) functional, the restored regularized strongly constrained and appropriately normed (r$^2$SCAN), in transition metal oxide (TMO) systems and compare its performance against SCAN. Specifically, we benchmark the r$^2$SCAN-calculated oxidation enthalpies, lattice parameters, on-site magnetic moments, and band gaps of binary 3\textit{d} TMOs against the SCAN-calculated and experimental values. Additionally, we evaluate the optimal Hubbard \emph{U} correction required for each transition metal (TM) to improve the accuracy of the r$^2$SCAN functional, based on experimental oxidation enthalpies, and verify the transferability of the \emph{U} values by comparing against experimental properties on other TM-containing oxides. Notably, including the \textit{U}-correction to r$^2$SCAN increases the lattice parameters, on-site magnetic moments and band gaps of TMOs, apart from an improved description of the ground state electronic state in narrow band gap TMOs. The r$^2$SCAN and r$^2$SCAN+\textit{U} calculated oxidation enthalpies follow the qualitative trends of SCAN and SCAN+\emph{U}, with r$^2$SCAN and r$^2$SCAN+\textit{U} predicting marginally larger lattice parameters, smaller magnetic moments, and lower band gaps compared to SCAN and SCAN+\textit{U}, respectively. We observe that the overall computational time (i.e., for all ionic+electronic steps) required for r$^2$SCAN(+\textit{U}) to be lower than SCAN(+\textit{U}). Thus, the r$^2$SCAN(+\textit{U}) framework can offer a reasonably accurate description of the ground state properties of TMOs with better computational efficiency than SCAN(+\textit{U}).

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