data_input _cell_length_a 3.9557 _cell_length_b 3.9557 _cell_length_c 3.9557 _cell_angle_alpha 90.0000 _cell_angle_beta 90.0000 _cell_angle_gamma 90.0000 _cell_volume 61.90 _symmetry_cell_setting 'cubic' _symmetry_Int_Tables_number 225 _symmetry_space_group_name_H-M 'Fm-3m ' loop_ _atom_site_type_symbol _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy Mg Mg1 0.0000 0.0000 0.0000 1.0000 O O1 0.5000 0.5000 0.5000 1.0000