**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** |
Mixed-space Approach to Phonons for Polar Materials and its Connection with the Calculations of Seebeck Coefficient |

**Author(s)** |
Yi Wang, Long Qing Chen, Zi-Kui Liu |

**On-Site Speaker (Planned)** |
Yi Wang |

**Abstract Scope** |
For decades, the supercell approach to calculating phonon frequencies has not been able to adequately account for the long range dipole–dipole interactions which lead to the well-known LO–TO splitting for polar insulators. This problem is solved with the proposed parameter-free mixed-space approach which makes full use of the accurate force constants from the real-space and the dipole-dipole interactions in reciprocal space. The mixed-space approach also made it convenient for the lattice thermal conductivity calculations where the third-order force constants are needed and were employed by several software packages. With the phonon frequency being calculated, the effect of thermal expansion the Seebeck coefficient can be accounted straightforwardly. The Seebeck coefficient represents the magnitude of an induced thermoelectric voltage in response to a temperature difference across a material and is a key property of thermoelectric materials. Its theoretical description has been based on the differential electrical conductivity given by Cutler and Mott. Here we derive a rigorous thermodynamic formalism for the parameter-free calculation of the Seebeck coefficient based on the electronic density-of-states from first-principles calculations, established on recent studies in the literature on the relation between the Seebeck coefficient and chemical potential of electrons. |

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