# Phonons of the anomalous element cerium

Title | Phonons of the anomalous element cerium |

Publication Type | Journal Article |

Year of Publication | 2011 |

Authors | Krisch M, Farber DL, Xu R, Antonangeli D, Aracne CM, Beraud A, Chiang TC, Zarestky J, Kim DY, Isaev EI, Ahuja R, Johansson B |

Journal Title | Proceedings of the National Academy of Sciences of the United States of America |

Volume | 108 |

Pages | 9342-9345 |

Date Published | 06 |

Type of Article | Article |

ISBN Number | 0027-8424 |

Accession Number | ISI:000291341400012 |

Keywords | alpha-gamma-transition, CE, dynamics, generalized gradient approximation, kondo, LATTICE, volume-collapse |

Abstract | Many physical and chemical properties of the light rare-earths and actinides are governed by the active role of f electrons, and despite intensive efforts the details of the mechanisms of phase stability and transformation are not fully understood. A prominent example which has attracted a lot of interest, both experimentally and theoretically over the years is the isostructural gamma-alpha transition in cerium. We have determined by inelastic X-ray scattering, the complete phonon dispersion scheme of elemental cerium across the gamma -> alpha transition, and compared it with theoretical results using ab initio lattice dynamics. Several phonon branches show strong changes in the dispersion shape, indicating large modifications in the interactions between phonons and conduction electrons. This is reflected as well by the lattice Gruneisen parameters, particularly around the X point. We derive a vibrational entropy change Delta S-vib(gamma-alpha) approximate to (0.33 +/- 0.03)k(B), illustrating the importance of the lattice contribution to the transition. Additionally, we compare first principles calculations with the experiments to shed light on the mechanism underlying the isostructural volume collapse in cerium under pressure. |

URL | <Go to ISI>://000291341400012 |

DOI | 10.1073/pnas.1015945108 |

Alternate Journal | Proc. Natl. Acad. Sci. U. S. A. |