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MM: Fachverband Metall- und Materialphysik
MM 34: Development of Calculation Methods
MM 34.7: Vortrag
Freitag, 21. März 2025, 12:00–12:15, H10
Spectral properties from an efficient analytical representation of the GW self-energy within a multipole approximation — •Dario Alejandro Leon1, Kristian Berland1, and Claudia Cardoso2 — 1Norwegian University of Life Sciences, As, Norway — 2S3 Centre, Istituto Nanoscienze, CNR, Modena, Italy
We propose an efficient analytical representation of the frequency-dependent GW self-energy via a multipole approximation (MPA-Σ). Similar to the earlier developed multipole approach for the screening interaction W (MPA-W) [Phys. Rev. B 104, 115157 (2021)], the multipole-Padé model for the self-energy is interpolated from a small set of values evaluated numerically in the complex frequency plane. As for MPA-W , we show that an appropriate choice of the frequency sampling is paramount to guarantee computational efficiency and high level of accuracy in the description of the self-energy. Crucially, MPA-Σ enables a multipole representation for the interacting Green’s function G (MPA-G), providing straightforward evaluation of all the spectral properties. Combining the MPA-W and MPA-Σ schemes considerably reduces the cost of full-frequency self-energy calculations, especially when targeting spectral band structures in a wide energy range. We validate the MPA-Σ approach in bulk Si, Na and Cu, monolayer MoS2, the NaCl ion-pair and the F2 molecule, as prototypical semiconducting and metallic materials of different dimensionality. Moreover, toy MPA-Σ models with one and two poles and their corresponding MPA-G solutions, are used to examine the quasiparticle picture in different situations.
Keywords: first principle calculations; Green's function formalism; GW self-energy; Analytical representation; Spectral band structure