Year: 2026
Type: preprint
Abstract: The frequency-dependent absorption and emission of light determine the colors of matter and underpin today's technologies, from solar cells to light-emitting diodes. Predicting optical properties from first principles remains a computational challenge, especially for large and disordered systems. The $GW$ plus Bethe-Salpeter equation ($GW$-BSE) approach provides predictive accuracy for optical properties, but conventional implementations become costly as system size grows. Here, we present a $GW$-BSE framework combining real-time propagation, atom-centered basis sets, and a locally optimized real-space resolution of the identity. The cost of each propagation step scales quadratically with system size and roughly equals the cost of one self-consistent-field iteration in a density-functional calculation with a semilocal functional. This computational efficiency allows us to calculate the absorption spectrum of a nanographene containing 4616 atoms and opens a path toward routine calculations of optical properties for large disordered systems.
Source: arXiv (Cornell University)
Institution: University of Regensburg
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G3392515402, G3899157429, Quantensimulationen ultraschneller Exzitonendynamik mit atomarer Auflösung, SFB 1277: Emergente relativistische Effekte in der Kondensierten Materie: Von grundlegenden Aspekten zu elektronischer Funktionalität, GRK 2905: Ultraschnelle Nanoskopie: von EinteilchenDynamik zu kooperativen Prozessen, G918256271
OpenAlex ID: W7221173889