**About this Abstract** |

**Meeting** |
**2018 TMS Annual Meeting & Exhibition
** |

**Symposium
** |
**Hume-Rothery Award Symposium: Computational Thermodynamics and Its Implications to Kinetics, Properties, and Materials Design
** |

**Presentation Title** |
Anharmonic Phonons in Cuprite |

**Author(s)** |
Claire Nicole Saunders, Dennis Kim, Olle Hellman, Hillary Smith, Tian Lan, Doug Abernathy, Brent Fultz |

**On-Site Speaker (Planned)** |
Claire Nicole Saunders |

**Abstract Scope** |
We report an extremely large anharmonicity of optical phonons in cuprite, Cu_{2}O. Phonon dispersions were measured at 10, 300, and 700 K by rotating a single crystal in the ARCS spectrometer at ORNL. Ab initio calculations of harmonic phonons accounted for the dispersions at 10 K. At 300 K, however, large broadenings of phonon energies made it impossible to use harmonic or quasiharmonic interpretations. The broadening was calculated from the cubic anharmonicity using the stochastic Temperature Dependent Effective Potential method (quasiharmonic phonons in an anharmonic potential), but the experimental broadening was considerably larger than these calculations. Results will be compared from ongoing ab initio molecular dynamics calculations and experimental phonon linewidths with full background corrections. Cuprite is stable to a temperature of 1503 K, but the phonon spectrum at 700 K is so broad that it may not be interpretable with phonons. Implications for vibrational entropy will be discussed. |

**Proceedings Inclusion?** |
Planned: Supplemental Proceedings volume |