The GW-Bethe-Salpeter Equation (BSE) (GW-BSE for short) is a state-of-the-art approach to calculate low-lying vertical excited states of molecular systems. Compared to Time-Dependent Density Functional Theory (TDDFT), it offers major improvements in the description of charge-transfer states. In the commonly implemented diagonal approximations to the electronic self-energy (G0W0), GW–BSE calculations depend heavily on the choice of a density functional approximation. This shortcoming is overcome by solving the GW equations self-consistently through the quasiparticle self-consistent GW-BSE (qsGW–BSE) method. qsGW typically predicts orbital energies more accurately than G0W0, and qsGW-BSE is more accurate for excitation energies[1,2]. Due to its typically high computational cost, it has however only been applied to rather small molecules so far.
Now, with a new qsGW-BSE implementation ADF, you can perform qsGW-BSE calculations on large molecules, as demonstrated by calculating the lowest excitation energies of the six chromophores of the photosystem II (PSII) reaction center (RC) with nearly 500 atoms and 2000 correlated electrons [3,4]. The calculated qsGW-BSE vertical excitation energies are in excellent agreement with experientally measured spectra for Chlorophyll monomers and dimers in the gas phase.
The new GW-BSE implementation will be available in the next release of the Amsterdam Modeling Suite. Contact us if you want to test qsGW-BSE with one of our development snapshots.
Learn more? Check out the webinar by Arno Förster on GW & BSE on 26 October!
 X. Gui, C. Holzer, W. Klopper, Accuracy Assessment of GW Starting Points for Calculating Molecular Excitation Energies Using the Bethe-Salpeter Formalism, JCTC, 2018, 14(4), 2127
 A. Förster, L. Visscher, Exploring the statically screened G3W2 correction to the GW self-energy : Charged excitations and total energies of finite systems, PRB, 2022, 105, 125121
 A. Förster, L. Visscher, Low-Order Scaling Quasiparticle Self-Consistent GW for Molecules, Frontiers in Chemistry, 2021, 9: 736591 (See also: news item)
 A. Förster, L. Visscher, Quasiparticle Self-Consistent GW-Bethe-Salpeter equation calculations for large chromophoric systems, JCTC, 2022, ASAP