Institute of Physical Chemistry, Theoretical Chemistry Group , Karlsruhe Institute of Technology (KIT) , KIT Campus South , P.O. Box 6980, D-76049 Karlsruhe , Germany.
Centre for Advanced Study (CAS) at The Norwegian Academy of Science and Letters , Drammensveien 78 , N-0271 Oslo , Norway.
J Chem Theory Comput. 2018 Apr 10;14(4):2127-2136. doi: 10.1021/acs.jctc.8b00014. Epub 2018 Mar 15.
The performance of the Bethe-Salpeter equation (BSE) approach for the first-principles computation of singlet and triplet excitation energies of small organic, closed-shell molecules has been assessed with respect to the quasiparticle energies used on input, obtained at various levels of GW theory. In the corresponding GW computations, quasiparticle energies have been computed for all orbital levels by means of using full spectral functions. The assessment reveals that, for valence excited states, quasiparticle energies obtained at the levels of eigenvalue-only self-consistent (ev GW) or quasiparticle self-consistent theory (qs GW) are required to obtain results of comparable accuracy as in time-dependent density-functional theory (TDDFT) using a hybrid functional such as PBE0. In contrast to TDDFT, however, the BSE approach performs well not only for valence excited states but also for excited states with Rydberg or charge-transfer character. To demonstrate the applicability of the BSE approach, computation times are reported for a set of aromatic hydrocarbons. Furthermore, examples of computations of ordinary photoabsorption and electronic circular dichroism spectra are presented for (C) and C, respectively.
用第一性原理计算小分子、闭壳层分子的单重态和三重态激发能时，评估了 Bethe-Salpeter 方程 (BSE) 方法对于输入的准粒子能的表现，这些准粒子能是在各种 GW 理论水平上获得的。在相应的 GW 计算中，通过使用全谱函数，对所有轨道能级的准粒子能进行了计算。评估结果表明，对于价激发态，需要在单特征值自洽 (evGW) 或准粒子自洽理论 (qsGW) 水平上获得准粒子能，才能获得与使用混合泛函（如 PBE0）的时间相关密度泛函理论 (TDDFT) 相当的精度。然而，与 TDDFT 不同的是，BSE 方法不仅对价激发态，而且对具有 Rydberg 或电荷转移特性的激发态也能很好地发挥作用。为了证明 BSE 方法的适用性，报告了一组芳烃的计算时间。此外，还分别为 (C) 和 C 展示了普通光吸收和电子圆二色性谱的计算实例。
