Real-Space Based Benchmark of G0W0 Calculations on GW100: Effects of Semicore Orbitals and Orbital Reordering,Journal of Chemical Theory and Computation

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Real-Space Based Benchmark of G0W0 Calculations on GW100: Effects of Semicore Orbitals and Orbital Reordering
Journal of Chemical Theory and Computation ( IF 5.7 ) Pub Date : 2019-09-04 , DOI: 10.1021/acs.jctc.9b00520
Weiwei Gao ₁ , James R. Chelikowsky _{1,

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Affiliation

Using an implementation based on real-space wave functions, we perform G₀W₀ calculations of the HOMO and LUMO energies of molecules and atoms in the GW100 set. Our main conclusions are as follows: (1) Different implementations of the G₀W₀ approximation show much better agreements for HOMO (highest occupied molecular orbital) energies than for LUMO (lowest unoccupied molecular orbital) energies. The mean absolute differences between the results calculated with different pseudopotential codes range from 100 to 200 meV. For delocalized LUMOs, all-electron codes that use local orbital basis tend to predict much higher energies than those calculated with plane-wave basis or real-space methods. (2) The effects of semicore electrons in pseudopotentials can explain some of the large discrepancies between results calculated with different GW implementations. For molecules or atoms that include I, Xe, and Ga, pseudopotential-based calculations that exclude semicore electrons produce results that agree better with all-electron calculations. For polar molecules such as NaCl and BrK, however, it is necessary to include semicore electrons for alkaline metal elements to get correct LUMO energies. (3) More than 20 molecules show rearrangement of the order between LUMO (or HOMO) with other orbitals due to GW corrections. Such orbitals that switch order with LUMO are unbound and delocalized in space. The predicted LUMO GW levels (or electron affinity) can be corrected by 2.0 eV if we consider the rearrangement of orbitals in GW calculations. In all, our work clarifies some of the discrepancies between different GW codes and sets a benchmark for real-space implementations of the G₀W₀ approximation.

中文翻译：

GW100上G0W0计算的基于实空间的基准：半核轨道和轨道重排的影响

使用基于实空间波函数的实现，我们对GW100集中的分子和原子的HOMO和LUMO能量进行G ₀ W ₀计算。我们的主要结论如下：（1）G ₀ W _0的不同实现近似显示，HOMO（最高占据的分子轨道）能量的协议要好于LUMO（最低未占用的分子轨道）能量的协议。用不同的伪电位代码计算的结果之间的平均绝对差为100至200 meV。对于离域LUMO，使用局部轨道基础的全电子代码倾向于预测比平面波基础或实空间方法计算的能量高得多的能量。（2）准电势中半核电子的影响可以解释使用不同的GW实现方法计算出的结果之间的某些较大差异。对于包含I，Xe和Ga的分子或原子，排除半芯电子的基于伪势的计算得出的结果与全电子计算更吻合。但是，对于NaCl和BrK等极性分子，必须包含用于碱金属元素的半芯电子，以获取正确的LUMO能量。（3）由于GW校正，超过20个分子显示LUMO（或HOMO）与其他轨道之间的顺序重排。此类与LUMO切换顺序的轨道在空间中不受约束和局域化。如果我们考虑GW计算中的轨道重排，则预测的LUMO GW水平（或电子亲和力）可以通过2.0 eV进行校正。总而言之，我们的工作澄清了不同GW代码之间的某些差异，并为G的实际空间实现奠定了基准此类与LUMO切换顺序的轨道在空间中不受约束和局域化。如果我们考虑GW计算中的轨道重排，则预测的LUMO GW水平（或电子亲和力）可以通过2.0 eV进行校正。总而言之，我们的工作澄清了不同GW代码之间的某些差异，并为G的实际空间实现奠定了基准此类与LUMO切换顺序的轨道在空间中不受约束和局域化。如果我们考虑GW计算中的轨道重排，则预测的LUMO GW水平（或电子亲和力）可以通过2.0 eV进行校正。总而言之，我们的工作澄清了不同GW代码之间的某些差异，并为G的实际空间实现奠定了基准₀ W ₀近似值。

更新日期：2019-09-04

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