About this Abstract |
Meeting |
2023 TMS Annual Meeting & Exhibition
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Symposium
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Neutron and X-ray Scattering in Materials Science
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Presentation Title |
Temperature Dependence of Anharmonic Effects in NaBr by Inelastic Neutron Scattering and Interatomic Potentials from Machine Learning |
Author(s) |
Vladimir Ladygin, Claire Sounders, Camille Bernal-Choban, Douglas Abernathy, Michael Manley, Brent Fultz |
On-Site Speaker (Planned) |
Vladimir Ladygin |
Abstract Scope |
The rocksalt phase of NaBr has highly anharmonic phonons. Its thermal expansion is well explained by anharmonic perturbation theory [1] DOI: 10.1103/PhysRevLett.125.085504. It also displays a new phenomenon from strong anharmonicity: intrinsic localized modes and intermodulation phonon sidebands. These features occur in pairs, resulting from anharmonic interactions of TA and TO phonons [2] DOI: 10.1103/PhysRevB.103.134302. Here we describe another effect of high temperatures on the phonon dispersions of NaBr measured by inelastic neutron scattering (INS). Also, we have found new spectral features in the optical phonon branches, including patches of diffuse intensity and distinct changes in the shapes of the dispersions. These features have now been measured by INS at multiple temperatures to confirm the original results, and monitor their evolution with temperature. These anharmonic phonon spectra are being simulated with ab initio and machine learning driven molecular dynamics methods. This work is supported by DOE BES award No. DE-FG02-03ER46055. |
Proceedings Inclusion? |
Planned: |
Keywords |
Characterization, Modeling and Simulation, Machine Learning |