Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 29: Poster II

HL 29.38: Poster

Tuesday, March 18, 2025, 18:00–20:00, P1

Visualizing Atomic-Scale Charge Fluctuations in Real-Space Dielectric Response — •Bernadette Christ and Claudia Rödl — Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany

The wave-vector and frequency-dependent dielectric function contains a plethora of information on the response of a given material to external perturbing electromagnetic fields that is rarely fully exploited. Its off-diagonal elements are known as local-field effects and encode the atomic-scale charge fluctuations that occur due to light-matter interaction or screening within the material.

We aim for developing a tool to visualize the impact of such an external perturbation on the electron density in the material in real space. In a first step, we calculate the independent-particle dielectric response function from first principles using density-functional theory. In this mean-field approach, we expect to see how interband transitions excite individual orbitals and how collective excitations such as plasmon waves propagate in the material. Later on, we will also consider inclusion of many-body effects in the evaluation of the response function to visualize the formation of excitons. This will help us to better understand the intricate interplay between the numerous electronic degrees of freedom and contribute to the analysis of spectroscopic experiments. As first benchmarks, we will study bulk semiconductors heading for more complex, technologically relevant materials systems afterwards.

Keywords: light-matter interaction; ab initio calculation; density-functional theory; dielectric response; code development