Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.42: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster E

Properties of stable ensembles of Euclidean random matrices modeling the vibrations in low-temperature glass — •Philipp Baumgärtel, Florian Vogel, and Matthias Fuchs — Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany

Using coupled disordered harmonic oscillators we investigate the vibrational properties of amorphous solids. Earlier findings suggest that this Euclidean random matrix ensemble features low temperature vibrational anomalies of glasses. By exact numerical diagonalization and a finite size study we analyze the spectra of the harmonic oscillators [1]. We observe a low-frequency regime of extended modes leading to a Debye like vibrational density of states. At larger frequencies the density of states shows an excess over the Debye behavior resembling Wigner's semicircle law. We discuss that the corresponding modes follow the statistics known from the Gaussian orthogonal ensemble. We reveal that the sound waves are damped by Rayleigh scattering even though the ERM system is purely harmonic. Additional calculations performed in two spatial dimension suggest that the two dimensional systems behave very similar to the three dimensional ones.

In conclusion, the Euclidean random matrix model captures salient features of the vibrational phenomena in glass at low temperatures.

[1] P. Baumgärtel, F. Vogel and M. Fuchs. arXiv:2309.08028, 2023

Keywords: Euclidean random matrix; Vibrations; Exact numerical diagonalization