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O: Fachverband Oberflächenphysik
O 49: Plasmonics and nanooptics: Light-matter interaction, spectroscopy I
O 49.4: Talk
Tuesday, March 10, 2026, 15:15–15:30, HSZ/0403
Quantum-electrodynamical density-functional theory for periodic solid-state materials — •Benshu Fan1, I-Te Lu1, Michael Ruggenthaler1, and Angel Rubio1,2 — 1Max Planck Institute for the Structure and Dynamics of Matter — 2Center for Computational Quantum Physics (CCQ), The Flatiron Institute
Quantum-electrodynamical density-functional theory (QEDFT) has emerged as a powerful first-principles framework for describing properties of materials coupled to quantized electromagnetic fields. While it has been successfully applied to capture cavity-induced modifications of electronic structures mainly for atoms and molecules, a consistent treatment of phonon-related and optical properties for periodic solids remains elusive. In this work, we present a unified QEDFT framework that incorporates collective light-matter coupling in the electronic ground state, density functional perturbation theory for phonons, and real-time time-dependent QEDFT for optical excitations. This approach enables ab initio calculations of cavity-modified electronic and phononic dispersions, Born effective charges, dielectric tensors, and both non-resonant and resonant optical absorption spectra for solids. Using wurtzite gallium nitride (GaN) embedded in an optical cavity as an example, we show how the quantized vacuum field reshapes electronic and phononic properties and gives rise to possible experimentally observable signatures in the dielectric function and absorption spectra. Our results establish QEDFT as a general first-principles framework for exploring and predicting cavity-modified properties of quantum materials.
Keywords: QEDFT; DFPT; TDDFT; cavity