Sponsor
Y. X. acknowledges 1) the support from the US National Science Foundation through award CBET-2445361, 2) the support from the Faculty Development Program at Portland State University, and 3) the computing resources provided by Bridges2 at Pittsburgh Supercomputing Center (PSC) through allocations mat220006p and mat220008p from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by National Science Foundation grants 2138259, 2138286, 2138307, 2137603, and 2138296.
Published In
Physical Review B
Document Type
Pre-Print
Publication Date
12-15-2025
Subjects
Lattice Thermal Transport
Abstract
The breakdown of the quasiparticle approximation (QPA) for phonons in strongly anharmonic materials necessitates advanced first-principles frameworks for accurate lattice dynamics and thermal transport predictions. We develop a comprehensive beyond-quasiparticle approximation (BQPA) approach incorporating both three- (3ph) and four-phonon (4ph) interactions and apply it to investigate lattice thermal conductivity (κL) in MgO, PbTe, and AgCl – materials that span a broad spectrum of anharmonicity, from weak to severe anharmonic regimes with overdamped phonons. We reveal that while BQPA consistently increases κL relative to QPA due to phonon softening when considering only 3ph interactions, the inclusion of additional 4ph interactions hardens the phonon spectrum and suppresses this enhancement, bringing BQPA and QPA predictions into close agreement via subtle spectral competition effects across all three compounds. These findings highlight that accurate modeling of κL in strongly anharmonic materials requires treating both full phonon spectral function and higher-order anharmonicity on equal footing. Our work establishes a systematic framework for modeling thermal transport in systems with overdamped phonons and provides critical insights for materials design beyond the limits of conventional phonon transport theory.
Rights
© Copyright the author(s) 2025
DOI
10.1103/r3sd-ftgb
Persistent Identifier
https://archives.pdx.edu/ds/psu/44394
Publisher
American Physical Society (APS)
Citation Details
Published as: Xia, Y. (2025). Lattice thermal transport beyond the quasiparticle approximation: Nontrivial spectral competition between three- and four-phonon interactions. Physical Review B, 112(24).
Description
This is the author’s version of a work that was accepted for publication. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as: Lattice thermal transport beyond the quasiparticle approximation: Nontrivial spectral competition between three- and four-phonon interactions. Physical Review B, 112(24).