Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I) Ouyang, Niuchang Zeng, Zezhu Wang, Chen Wang, Qi Chen, Yue The phonon transport mechanisms and ultralow lattice thermal conductivities (κL) in silver halide AgX (X=Cl,Br,I) compounds are not yet well understood. Herein, we study the lattice dynamics and thermal property of AgX under the framework of perturbation theory and the two-channel Wigner thermal transport model based on accurate machine learning potentials. We find that an accurate extraction of the third-order atomic force constants from largely displaced configurations is significant for the calculation of the κL of AgX, and the coherence thermal transport is also non-negligible. In AgI, however, the calculated κL still considerably overestimates the experimental values even including four-phonon scatterings. Molecular dynamics (MD) simulations using machine learning potential suggest an important role of the higher-than-fourth-order lattice anharmonicity in the low-frequency phonon linewidths of AgI at room temperature, which can be related to the simultaneous restrictions of the three- and four-phonon phase spaces. The κL of AgI calculated using MD phonon lifetimes including full-order lattice anharmonicity shows a better agreement with experiments. American Physical Society 2023 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/14605 Ouyang N, Zeng Z, Wang C, Wang Q, Chen Y. Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I). <i>Physical Review B</i>. 2023;108(17). doi:<a href="https://doi.org/10.1103/PhysRevB.108.174302">10.1103/PhysRevB.108.174302</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevB.108.174302 info:eu-repo/semantics/altIdentifier/issn/2469-9950 info:eu-repo/semantics/altIdentifier/e-issn/2469-9969 info:eu-repo/semantics/altIdentifier/wos/001101152500001 info:eu-repo/semantics/closedAccess