Dresden 2020 – wissenschaftliches Programm
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MM 59.5: Vortrag
Donnerstag, 19. März 2020, 16:45–17:00, IFW A
Anharmonic phonons at elevated temperatures in Al — •Michael Leitner1 and Albert Glensk2,3 — 1Technische Universität München, 85748 Garching, Germany — 2Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland — 3Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany
The importance of anharmonicity for describing fundamental materials properties, starting from finite heat conductivity due to phonon-phonon scattering, can hardly be overemphasized. For crystalline matter, the principal microscopic gauge is constituted by the broadening in energy of the phonon dispersions, corresponding to q-dependent phonon lifetimes.
Here the case of elemental Al at temperatures up to the melting point will be considered. Experimental data obtained by inelastic neutron scattering will be compared to calculations of q-dependent line broadenings on the basis of density-functional theory. The agreement with spectra computed by ab initio molecular dynamics is satisfactory, while the standard approach of perturbation theory gives significant discrepancies. Finally, an analysis of the atomic interaction constants will show how numerically efficient phenomenological potentials can be constructed that allow to compute anharmonic properties beyond the limitations of perturbation theory at very small computational effort.
A. Glensk et al., to be published in Phys. Rev. Lett. (2019)