data_OPT_STEP_7 _cell_length_a 4.14877414 _cell_length_b 4.14877414 _cell_length_c 4.14877414 _cell_angle_alpha 90.00000000 _cell_angle_beta 90.00000000 _cell_angle_gamma 90.00000000 _symmetry_cell_setting 'cubic' _symmetry_space_group_name_H-M 'F M 3 M' _symmetry_Int_Tables_number 225 loop_ _atom_site_type_symbol _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Mg MG1 0.00000000 0.00000000 0.00000000 O O2 0.50000000 0.50000000 0.50000000