Abstract: Identifying materials with ultralow thermal conductivities κ is the pivotal challenge in the development of more efficient thermoelectric devices. One strategy to achieve this goal is to find materials with a high level of anharmonicity, and therefore reduced phonon lifetime and κ.
To help discover such materials, we calculate the anharmonicity of materials ranging from simple binary compounds to complex perovskites using the high-throughput framework FHIvibes. The framework automatically generates an accurate harmonic model for a material’s vibrational properties, from which we determine its anharmonicity by statistically comparing the harmonic and ab initio forces of thermally displaced structures. Our screening not only demonstrates that anharmonicity is more prevalent in material space than previously thought, but also shows that the developed metric strongly correlates with various thermal properties.
Using classes of simple binaries as an example, we show that the anharmonicity of a material can be related to its atomic, bulk, and harmonic properties via the sure independence screening and sparsifying operator (SISSO) approach, thus facilitating an even more efficient screening.