Work

Efficient analytic continuation approach to Bethe–Salpeter excitation spectra in selected energy windows

Year: 2026

Type: article

Abstract: We explore the merits of building the Bethe-Salpeter absorption spectrum in a specific energy range using analytic continuation techniques. Specifically, we calculate iteratively a few ᾱ̄(zk) polarizability tensors for a coarse set of (zk) frequencies in the complex-plane. These data allow the construction of a continued-fraction representation for ᾱ̄(z) that is used to calculate the absorption spectrum close to the real energy axis in the desired energy range. The number and location of these sampling complex frequencies are discussed. The importance of building a continued-fraction representation of the full polarizability tensor with matrix-valued coefficients is emphasized. We show how to extract the poles of the continued fraction as a tool for analyzing the resulting spectra. We study as examples the valence excitations of a paradigmatic dipeptide, the C60 fullerene and its [6,6]-phenyl-C61-butyric acid methyl ester derivative, together with the description of the surface plasmon resonance of the Ag20 silver cluster. Furthermore, the high-energy C60 X-ray absorption spectrum is explored.

Source: The Journal of Chemical Physics

DOI: 10.1063/5.0340331

Authors: Ivan Duchemin, Xavier Blase

Institutions: Commissariat à l'Énergie Atomique et aux Énergies Alternatives, CEA Grenoble, Institut de Recherche Interdisciplinaire de Grenoble, Centre National de la Recherche Scientifique, Institut Néel

Language: English

Topic: Advanced Chemical Physics Studies

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funder: Grand Équipement National De Calcul Intensif

Awards: G2429624233, G3452515519