GPa 36 . This variability is justified by the existence of two low-pressure phases with different compressibility, whose relative stability at ambient pressure is influenced by the template species. Ab initio investigations at the PW91 DFT level on ideal, template-free silica sodalite found that the zeropressure phase belongs to the high symmetry Im3̅ m space group and undergoes a phase transition at 0.12 GPa to the Im3̅ m group, with a loss of inversion symmetry. Additionally, two other phase transitions were identified with further compression up to about 4 GPa, preserving the lattice symmetry I4̅ 3m. The I4̅ 3m phase was found to be less compressible, with a computed bulk modulus of 113 GPa, closely resembling the experimental value of ~132 GPa. The three high-pressure I4̅ 3m phases became progressively more compressible, with the bulk modulus decreasing from 67 to 15