The MC-rattle method, as implemented in HiPhive, generates realistic random atomic displacements with a Monte Carlo step to avoid unrealistically small interatomic distances which may lead to large repulsive forces. Initially, we explored this method due to its capability to produce physically representative displacement patterns. However, we opted against its continued use for two primary reasons: (i) The difficulty of separating small and large displacement sets for the aforementioned separate fitting of harmonic and anharmonic IFCs and (ii) the reliance on material-dependent empirical amplitude for rattling. For (ii), we need to introduce a second scheme of tuning the standard deviation for MC rattle to ensure acceptable outputs as shown in Figure , but this is difficult to automate. We note that the predicted thermal properties, including lattice thermal conductivity, are found highly sensitive to these rattling settings (see Figure for further details). Therefore, we have since opted to perturb supercells with consistent and fixed displacements regardless of material type.