Kshirsagar Aseem Rajan, Poloni Roberta
Université Grenoble Alpes, CNRS, Grenoble-INP, SIMaP, 38000 Grenoble, France.
J Phys Chem A. 2023 Mar 23;127(11):2618-2627. doi: 10.1021/acs.jpca.2c07526. Epub 2023 Mar 13.
We adopt the many-body perturbation theory in conjunction with the Bethe-Salpeter equation (BSE) to compute 57 excitation energies of a set of 37 molecules. By using the PBEh global hybrid functional and a self-consistent scheme on the eigenvalues in , we show a strong dependence of the BSE energy on the starting Kohn-Sham (KS) density functional. This arises from both the quasiparticle energies and the spatial localization of the frozen KS orbitals employed to compute the BSE. In order to address the arbitrariness in the mean field choice, we adopt an orbital-tuning scheme where the amount of Fock exchange, α, is tuned to impose that the KS HOMO matches the quasiparticle eigenvalue, thus fulfilling the ionization potential theorem in DFT. The performance of the proposed scheme yields excellent results and it is similar to M06-2X and PBEh with α = 75%, consistent with tuned values of α ranging between 60% and 80%.
我们采用多体微扰理论并结合贝叶斯 - 萨尔皮特方程（BSE）来计算一组37个分子的57个激发能。通过使用PBEh全局杂化泛函以及对特征值采用自洽方案，我们表明BSE能量强烈依赖于起始的科恩 - 沙姆（KS）密度泛函。这源于准粒子能量以及用于计算BSE的冻结KS轨道的空间局域化。为了解决平均场选择中的任意性问题，我们采用一种轨道调整方案，其中福克交换量α被调整，以使KS最高占据分子轨道（HOMO）与准粒子特征值匹配，从而在密度泛函理论（DFT）中满足电离势定理。所提出方案的性能产生了优异的结果，并且它与α = 75%时的M06 - 2X和PBEh相似，与α在60%至80%之间的调整值一致。
