First-Principles Simulation of Lattice Thermal Conductivity: Uncertainties from Different Flavors of Temperature-Dependent Force Constants

First-principles simulations of lattice thermal conductivity, κ_L, of highly anharmonic crystals have long been challenging in condensed matter physics. With recent theoretical advances, the calculation of κ_L has evolved into a sophisticated process requiring the consideration of high-order phonon-phonon scattering, anharmonic phonon renormalization, and the temperature-dependent potential energy surface. Interatomic force constants (IFCs), however, as a shared pillar of the above concepts, are ambiguously implemented in this process, resulting in nonnegligible discrepancies between different studies. Here, we revisit the ultralow κ_L of Tl₃VSe₄ and make a rigorous comparison using different flavors of IFCs. We find that the phonon spectrum obtained with 0 K IFCs is prone to get over stiffened after anharmonic renormalization, which leads to a doubled κ_L even with up to four-phonon scattering considered. Moreover, the different flavors of fitting 2nd-, 3rd-, and 4th-order IFCs at finite temperatures using force-displacement data leads to significantly dispersive κ_L. Our work illuminates how choosing different IFCs alters κ_L, which contributes to a better understanding of lattice dynamics simulation based on the perturbation theory.