Cell + Ionic relaxation with Orb v3; 0.03 eV/Å threshold; final energy = -536.0711 eV; energy change = -55.6215 eV; symmetry: P1 → Pm
Interstitially doped with S at ~5.0%; supercell [2, 2, 2]; dopant atoms = 3
Phonon band structure (supercell [2, 2, 2], Δ=0.01 Å); no imaginary modes; min freq = -0.04 THz