2018/09/13 by Tianli Feng, Xiaolong Yang, Xiulin Ruan
Engineering · Materials Science · Physics and Astronomy · #Acoustic Wave Resonator Technologies #Anharmonicity #Condensed matter physics #Materials science #Optics #Phonon #Phonon scattering #Physics #Scattering #Thermal Expansion and Ionic Conductivity #Thermal properties of materials #cond-mat.mtrl-sci
paper · pdf · doi:10.1063/1.5048799
arxiv created 2018/09/13 · openalex publication_date 2018/10/09 · arxiv updated 2018/11/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Phonon energies at finite temperatures shift away from their harmonic values due to anharmonicity. In this paper, we have realized the rigorous calculation of phonon energy shifts of silicon by three- and four-phonon scattering from first principles. The anharmonic fourth-order force constants are calculated by considering up to the fifth nearest neighbors. The results agree reasonably well with available data from inelastic neutron scattering throughout the Brillouin zone. Surprisingly, the frequency shifts of optical phonon modes near the Γ point are sensitive to the cutoff radius of the fourth-order force constants, in contrast to the four-phonon scattering rates, which nearly saturate when considering the second nearest neighbors. We have also compared the results with ab initio molecular dynamics simulations and found that the higher order of anharmonicity is important for optical phonons. Our work provides critical insight into the anharmonic phonon frequency shift and will have a significant impact on the thermal and optical applications.