lattice_vector 4.21041000 0.00000000 0.00000000 lattice_vector 0.00000000 4.21041000 0.00000000 lattice_vector 0.00000000 0.00000000 4.21041000 atom_frac 0.000000 0.000000 0.000000 Mg atom_frac 0.500000 0.000000 0.000000 O