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Nuclear quantum effect with pure anharmonicity and the anomalous thermal expansion of silicon.
Kim, D S; Hellman, O; Herriman, J; Smith, H L; Lin, J Y Y; Shulumba, N; Niedziela, J L; Li, C W; Abernathy, D L; Fultz, B.
Afiliação
  • Kim DS; Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA 91125; dennis.s.kim@icloud.com btf@caltech.edu.
  • Hellman O; Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA 91125.
  • Herriman J; Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA 91125.
  • Smith HL; Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA 91125.
  • Lin JYY; Neutron Data Analysis and Visualization Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831.
  • Shulumba N; Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, CA 91125.
  • Niedziela JL; Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831.
  • Li CW; Department of Mechanical Engineering, University of California, Riverside, CA 92521.
  • Abernathy DL; Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831.
  • Fultz B; Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, CA 91125; dennis.s.kim@icloud.com btf@caltech.edu.
Proc Natl Acad Sci U S A ; 115(9): 1992-1997, 2018 02 27.
Article em En | MEDLINE | ID: mdl-29440490
Despite the widespread use of silicon in modern technology, its peculiar thermal expansion is not well understood. Adapting harmonic phonons to the specific volume at temperature, the quasiharmonic approximation, has become accepted for simulating the thermal expansion, but has given ambiguous interpretations for microscopic mechanisms. To test atomistic mechanisms, we performed inelastic neutron scattering experiments from 100 K to 1,500 K on a single crystal of silicon to measure the changes in phonon frequencies. Our state-of-the-art ab initio calculations, which fully account for phonon anharmonicity and nuclear quantum effects, reproduced the measured shifts of individual phonons with temperature, whereas quasiharmonic shifts were mostly of the wrong sign. Surprisingly, the accepted quasiharmonic model was found to predict the thermal expansion owing to a large cancellation of contributions from individual phonons.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Tipo de estudo: Prognostic_studies Idioma: En Ano de publicação: 2018 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Tipo de estudo: Prognostic_studies Idioma: En Ano de publicação: 2018 Tipo de documento: Article