We utilized the Vienna ab simulation package (VASP) code to perform the DFT calculations with the plane wave basis set where the cut-off energy was set as 500 eV . For the exchange-correlation potential, we considered the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE) formulation . The energy convergence criterion and the force convergence criterion were set to 10 -8 eV and 10 -2 eV/Å, respectively. The Brillouin zone integrations were carried out using a dense K-point mesh within the Monkhorst-Pack scheme. A 5 × 5 × 5 K-mesh was used for the A 6 MO 6 unit cells, while a 2 × 5 × 5 K-mesh was used for their 2 × 1 × 1 supercells. A 6 × 6 × 6 K-mesh was used for the BaCuF 6 unit cells, while a 3 × 6 × 6 K-mesh was used for their 2 × 1 × 1 supercells. Since the considered cubic structures contain extensive lattice constants (a > 8Å) above K-meshes are sufficiently large. The density functional perturbation theory (DFPT) implemented in the VASP program was used to determine the elastic constants. The bulk modulus (K), Shear modulus (G), Young's modulus (Y), and Poisson's ratio (ν) of the materials were calculated based on the Hill method using the VASPKIT code . The phonon dissipation curves of the materials were obtained using Phonopy code .