Construction of meta-GGA functionals through restoration of exact constraint adherence to regularized SCAN functionals
Construction of meta-GGA functionals through restoration of exact constraint adherence to regularized SCAN functionals
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DOI：
10.1063/5.0073623
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发表时间：
2022-01-21
影响因子：
4.4
通讯作者：
Sun, Jianwei
中科院分区：
文献类型：
--
作者：
Furness, James W.;Kaplan, Aaron D.;Sun, Jianwei
强约束和适当赋范（SCAN）元GGA交换相关泛函[Sun等人，物理修订信函115，036402（2015）]被构建为两个单独的能量密度之间的化学环境确定的插值：一个精确地描述单轨道电子密度，另一个精确地描述缓慢变化的密度。为了保存确切的交换相关函数已知的约束，该插值的导数在缓慢变化的极限中消失。虽然理论上很方便，但这种选择引入了降低泛函效率的数值挑战。我们最近报道了对SCAN元GGA的修改，称为恢复正则化SCAN（r（2）SCAN）[Furness等人，《物理化学杂志》11，8208（2020）]，其将两个正则化引入到SCAN中，这以不恢复用于交换的缓慢变化的密度梯度展开的四阶项为代价来改善其数值性能。在这里，我们展示了密度泛函近似[正则化SCAN（rSCAN），r++SCAN，r（2）SCAN和r（4）SCAN]的进展的推导，其中增加了对精确条件的坚持，同时保持平滑插值。r（2）SCAN的更大平滑度似乎比SCAN或r（4）SCAN的附加精确约束导致更好的总体精度。
The strongly constrained and appropriately normed (SCAN) meta-GGA exchange-correlation functional [Sun et al., Phys. Rev. Lett. 115, 036402 (2015)] is constructed as a chemical environment-determined interpolation between two separate energy densities: one describes single-orbital electron densities accurately and another describes slowly varying densities accurately. To conserve constraints known for the exact exchange-correlation functional, the derivatives of this interpolation vanish in the slowly varying limit. While theoretically convenient, this choice introduces numerical challenges that degrade the functional's efficiency. We have recently reported a modification to the SCAN meta-GGA, termed restored-regularized-SCAN (r(2)SCAN) [Furness et al., J. Phys. Chem. Lett. 11, 8208 (2020)], that introduces two regularizations into SCAN, which improve its numerical performance at the expense of not recovering the fourth order term of the slowly varying density gradient expansion for exchange. Here, we show the derivation of a progression of density functional approximations [regularized SCAN (rSCAN), r++SCAN, r(2)SCAN, and r(4)SCAN] with increasing adherence to exact conditions while maintaining a smooth interpolation. The greater smoothness of r(2)SCAN seems to lead to better general accuracy than the additional exact constraint of SCAN or r(4)SCAN does.