The Electron Affinity as the Highest Occupied Anion Orbital Energy with a Sufficiently Accurate Approximation of the Exact Kohn-Sham Potential
The Electron Affinity as the Highest Occupied Anion Orbital Energy with a Sufficiently Accurate Approximation of the Exact Kohn-Sham Potential
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DOI：
10.1021/acs.jctc.9b00981
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发表时间：
2020-01-01
影响因子：
5.5
通讯作者：
Baerends, E. J.
中科院分区：
文献类型：
--
作者：
Amati, M.;Stoia, S.;Baerends, E. J.
负离子在密度泛函近似(DFA)中不能准确表示，如(半)局域密度泛函(LDA或GGA或Meta-GGA)。这是由于与精确的Kohn-Sham值相比，这些DFA的轨道能量太高(还不够负)。负离子通常具有正的DFA HOMO能量，因此它们是不稳定的。这些问题不会发生在精确的Kohn-Sham势下，此时阴离子的HOMO能量等于减去电子亲和势。因此，人们希望得到精确的Kohn-Sham势的足够精确的近似式。使用精确的KS势的良好近似值对轨道形状和密度有进一步的有利影响。值得注意的是，未占据轨道并不像在Hartree-Fock模型中那样过度扩散，它们具有混合泛函，甚至具有(半)局部密度泛函近似(LDFA)。我们证明了最近发展的B-GLLB-VWN近似[Gritsenko等人。J·化学。太棒了。精确的KS势能提供稳定的负离子，其HOMO轨道能量接近电子亲和力。
Negative ions are not accurately represented in density functional approximations (DFAs) such as (semi)local density functionals (LDA or GGA or meta-GGA). This is caused by the much too high orbital energies (not negative enough) with these DFAs compared to the exact Kohn-Sham values. Negative ions very often have positive DFA HOMO energies, hence they are unstable. These problems do not occur with the exact Kohn-Sham potential, the anion HOMO energy then being equal to minus the electron affinity. It is therefore desirable to develop sufficiently accurate approximations to the exact Kohn-Sham potential. There are further beneficial effects on the orbital shapes and the density of using a good approximation to the exact KS potential. Notably the unoccupied orbitals are not unduly diffuse, as they are in the Hartree-Fock model, with hybrid functionals, and even with (semi)local density functional approximations (LDFAs). We show that the recently developed B-GLLB-VWN approximation [Gritsenko et al. J. Chem. Phys. 2016, 144, 204114] to the exact KS potential affords stable negative ions with HOMO orbital energy close to minus the electron affinity.