data_IBr
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.42
_cell_length_b   5.42
_cell_length_c   8.43
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   IBr
_chemical_formula_sum   'I2 Br2'
_cell_volume   214.43
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  I  I2  1  0.71  0.56  0.07  1.0
  I  I3  1  0.0  0.13  0.86  1.0
  Br  Br0  1  0.71  0.56  0.52  1.0
  Br  Br1  1  0.0  0.13  0.3  1.0

data_IBr
_symmetry_space_group_name_H-M   Cm
_cell_length_a   9.39
_cell_length_b   5.42
_cell_length_c   8.43
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   IBr
_chemical_formula_sum   'I4 Br4'
_cell_volume   428.86
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  I  I0  2  0.14  0.0  0.86  1.0
  I  I1  2  0.35  0.5  0.07  1.0
  Br  Br2  2  0.14  0.0  0.3  1.0
  Br  Br3  2  0.35  0.5  0.52  1.0

I I Br Br