Finally, a smaller 7 × 7 × 7 mesh was used to compare the two-phonon joint density of states (w-JDoS) functions and averaged phonon-phonon interaction strengths for the pristine and filled models based on the CoSb3 conventional cell, and to investigate the effect of varying the atomic mass of the noble gas atoms in the filled models. The thermal conductivities calculated using these reduced meshes are within 1-5 % of those obtained using the 9 × 9 × 9 meshes, and the approximately twofold reduction in the number of grid points makes the post processing much less computationally intensive.