Lattice Thermal Conductivity and Thermoelectric Properties of Topological Semimetals*

Topological semimetals exhibit unique electronic and transport properties that make them promising candidates for advanced thermal management and thermoelectric applications. Here, we study theoretically the lattice thermal conductivities κL of topological materials including WTe₂, MoTe₂, Ta₃S₂, Bi₄I₄, and Bi₄Br₄. In particular, we compute κ_L based on the Debye temperatures obtained through various approaches, including mechanical properties, phonon spectra, and machine learning simulations. We further validate the results via first-principles density functional theory (DFT) calculations of κ_L via direction evaluations of the third-order anharmonic force constants. The results indicate that using Debye temperature remains an efficient and relatively accurate method for estimating the lattice thermal conductivity. Finally, we also compute other electronic and transport properties of the topological semimetals under study and discuss their potential in transverse thermoelectric applications.