Self-Consistent Phonon Spectral Functions and Thermal Transport Beyond the Quasiparticle Approximation
Abstract
Anharmonic lattice dynamics shapes phonon spectra and thermal transport, yet first-principles linewidth calculations typically assume phonon quasiparticles with sharply defined frequencies. Here, we introduce a self-consistent spectral function framework that determines interacting phonon spectral functions by dressing the internal lines of the three-phonon bubble self-energy with the spectra generated by the same interaction. The method self-consistently determines the real and imaginary parts of the self-energy on equal footing, eliminates the need for externally chosen smearing parameters to enforce energy conservation, and extends lattice dynamics and thermal transport calculations beyond the quasiparticle approximation. Applied to zincblende HgTe, self-consistency substantially broadens acoustic and optical phonon spectra, activates scattering channels inaccessible in the one-shot quasiparticle calculation, and reduces the lattice thermal conductivity by approximately a factor of five to the experimental scale while reproducing its temperature dependence, without explicitly invoking higher-order interactions. Mode-resolved spectral functions are further validated against the power spectra from direct molecular dynamics simulations. These results establish self-consistent spectral functions as a practical bridge between quasiparticle perturbation theory and fully dynamical simulations, and provide a framework readily generalizable to higher-order anharmonic processes.
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BibTeX
@misc{xia2026selfconsistent,
title = {{Self-Consistent Phonon Spectral Functions and Thermal Transport Beyond the Quasiparticle Approximation}},
author = {Yi Xia},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.10211},
eprint = {2607.10211},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.10211},
}
RIS
TY - UNPB
TI - Self-Consistent Phonon Spectral Functions and Thermal Transport Beyond the Quasiparticle Approximation
AU - Yi Xia
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2607.10211
UR - https://arxiv.org/abs/2607.10211
AB - Anharmonic lattice dynamics shapes phonon spectra and thermal transport, yet first-principles linewidth calculations typically assume phonon quasiparticles with sharply defined frequencies. Here, we introduce a self-consistent spectral function framework that determines interacting phonon spectral functions by dressing the internal lines of the three-phonon bubble self-energy with the spectra generated by the same interaction. The method self-consistently determines the real and imaginary parts of the self-energy on equal footing, eliminates the need for externally chosen smearing parameters to enforce energy conservation, and extends lattice dynamics and thermal transport calculations beyond the quasiparticle approximation. Applied to zincblende HgTe, self-consistency substantially broadens acoustic and optical phonon spectra, activates scattering channels inaccessible in the one-shot quasiparticle calculation, and reduces the lattice thermal conductivity by approximately a factor of five to the experimental scale while reproducing its temperature dependence, without explicitly invoking higher-order interactions. Mode-resolved spectral functions are further validated against the power spectra from direct molecular dynamics simulations. These results establish self-consistent spectral functions as a practical bridge between quasiparticle perturbation theory and fully dynamical simulations, and provide a framework readily generalizable to higher-order anharmonic processes.
ER -