We present a new assessment of the Fermi‐Löwdin orbital self‐interaction correction (FLO‐SIC) approach with an emphasis on its performance for predicting energies as a function of fractional occupation numbers (FONs) for various multielectron systems. Our approach is implemented in the massively parallelized NWChem quantum chemistry software package and has been benchmarked on the prediction of total energies, atomization energies, and ionization potentials of small molecules and relatively large aromatic systems. Within our study, we also derive an alternate expression for the FLO‐SIC energy gradient expressed in terms of gradients of the Fermi‐orbital eigenvalues and revisit how the FLO‐SIC methodology can be seen as a constrained unitary transformation of the canonical Kohn–Sham orbitals. Finally, we conclude with calculations of energies as a function of FONs using various SIC‐scaling methods to test the limits of the FLO‐SIC formalism on a variety of multielectron systems. We find that these relatively simple scaling methods do improve the prediction of total energies of atomic systems as well as enhance the accuracy of energies as a function of FONs for other multielectron chemical species.

中文翻译：

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Fermi-Löwdin 轨道自相互作用校正方法的分数占据数和自相互作用校正缩放方法

我们对 Fermi-Löwdin 轨道自相互作用校正 (FLO-SIC) 方法进行了新的评估，重点是其预测能量作为各种多电子系统的分数占据数 (FON) 函数的性能。我们的方法在大规模并行化的 NWChem 量子化学软件包中实施，并已在预测小分子和相对较大的芳烃系统的总能量、原子化能和电离势方面进行了基准测试。在我们的研究中，我们还推导出了 FLO-SIC 能量梯度的替代表达式，以费米轨道特征值的梯度表示，并重新审视 FLO-SIC 方法如何被视为规范 Kohn-Sham 的受约束幺正变换轨道。最后，最后，我们使用各种 SIC 缩放方法计算作为 FON 函数的能量，以测试 FLO-SIC 形式主义对各种多电子系统的限制。我们发现这些相对简单的缩放方法确实提高了对原子系统总能量的预测，并提高了能量作为其他多电子化学物质 FON 函数的准确性。