Yamamoto Yoh, Salcedo Alan, Diaz Carlos M, Alam Md Shamsul, Baruah Tunna, Zope Rajendra R
Department of Physics, The University of Texas at El Paso, El Paso, Texas 79968, USA.
Phys Chem Chem Phys. 2020 Aug 24;22(32):18060-18070. doi: 10.1039/d0cp02717k.
Recent regularization of the SCAN meta-GGA functional (rSCAN) has simplified the numerical complexities of the SCAN functional, alleviating SCAN's stringent demand on the numerical integration grids to some extent. The regularization of rSCAN, however, results in the breaking of some constraints such as the uniform electron gas limit, the slowly varying density limit, and coordinate scaling of the iso-orbital indicator. Here, we assess the effects of regularization on the electronic, structural, vibrational, and magnetic properties of molecules by comparing the SCAN and rSCAN predictions. The properties studied include atomic energies, atomization energies, ionization potentials, electron affinities, barrier heights, infrared intensities, dissociation and reaction energies, spin moments of molecular magnets, and isomer ordering of water clusters. Our results show that rSCAN requires less dense numerical grids and gives very similar results to those of SCAN for all properties examined with the exception of atomization energies, which are worsened in rSCAN. We also examine the performance of self-interaction-corrected (SIC) rSCAN with respect to SIC-SCAN using the Perdew-Zunger (PZ) SIC method. The PZSIC method uses orbital densities to compute one-electron self-interaction errors and places an even more stringent demand on numerical grids. Our results show that SIC-rSCAN gives marginally better performance than SIC-SCAN for almost all properties studied in this work with numerical grids that are on average half or less as dense as that needed for SIC-SCAN.
最近对SCAN元广义梯度近似泛函（rSCAN）的正则化简化了SCAN泛函的数值复杂性，在一定程度上缓解了SCAN对数值积分网格的严格要求。然而，rSCAN的正则化导致了一些约束条件的破坏，如均匀电子气极限、缓慢变化密度极限以及等轨道指标的坐标缩放。在此，我们通过比较SCAN和rSCAN的预测结果，评估正则化对分子的电子、结构、振动和磁性性质的影响。所研究的性质包括原子能量、原子化能、电离势、电子亲和能、势垒高度、红外强度、解离和反应能、分子磁体的自旋矩以及水团簇的异构体排序。我们的结果表明，rSCAN所需的数值网格密度较低，并且对于所有考察的性质，除了原子化能在rSCAN中变差外，rSCAN给出的结果与SCAN非常相似。我们还使用佩德韦-曾格（PZ）自相互作用校正（SIC）方法研究了自相互作用校正的（SIC）rSCAN相对于SIC-SCAN的性能。PZSIC方法使用轨道密度来计算单电子自相互作用误差，并且对数值网格有更严格的要求。我们的结果表明，对于这项工作中研究的几乎所有性质，SIC-rSCAN在数值网格平均密度仅为SIC-SCAN所需密度的一半或更低的情况下，表现略优于SIC-SCAN。
