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arXiv · 2305.16959

Connections and performances of Green's function methods for charged and neutral excitations

Enzo Monino·Pierre-François Loos
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Abstract

In recent years, Green's function methods have garnered considerable interest due to their ability to target both charged and neutral excitations. Among them, the well-established $GW$ approximation provides accurate ionization potentials and electron affinities and can be extended to neutral excitations using the Bethe-Salpeter equation (BSE) formalism. Here, we investigate the connections between various Green's function methods and evaluate their performance for charged and neutral excitations. Comparisons with other widely-known second-order wave function methods are also reported. Additionally, we calculate the singlet-triplet gap of cycl[3,3,3]azine, a model molecular emitter for thermally activated delayed fluorescence, which has the particularity of having an inverted gap thanks to a substantial contribution from the double excitations. We demonstrate that, within the $GW$ approximation, a second-order BSE kernel with dynamical correction is required to predict this distinctive characteristic.

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Enzo Monino, Pierre-François Loos. 2023-05-26. Connections and performances of Green's function methods for charged and neutral excitations. https://doi.org/10.1063/5.0159853

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