PGI-1 Talk: Friedrich Hanrath

Quantum Theory of Materials Seminar

Extension of FLAPW method FLEUR to phonon calculations of polar solids using DFPT

Phonons play a pivotal role in determining important properties of solids. In polar materials, phononic vibrations are altered by the interaction of macroscopic electric fields in the limit of long wavelengths. This gives rise to the characteristic splitting of longitudinal and transversal optical phonon frequencies.

Density function perturbation theory (DFPT) is a state-of-the-art approach to calculate many essential physical properties of solids from first principles. By using an ionic displacement perturbation, it has previously been employed in order to calculate phonons in the framework of the full-potential linearized augmented plane-wave method FLEUR [1, 2].

In this talk, this method is extended to a macroscopic homogeneous electric field perturbation allowing the calculation of static dielectric properties, Born effective charges and hence LO-TO-splitting. We present the current results for the static dielectric tensor for various semiconductors and insulators by comparing them with experimental results.

[1] D. Wortmann et al.,  10.5281/zenodo.7576163; www.flapw.de
[2] C.-R. Gerhorst et al., Electron.\ Struct. 6,  017001 (2024).

Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Email: s.bluegel@fz-juelich.de

Hanrath Friedrich
Phone: +49 2461 61-5115
Email: f.hanrath@fz-juelich.de