data_Mg2SeBr
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.67
_cell_length_b   7.67
_cell_length_c   7.67
_cell_angle_alpha   150.69
_cell_angle_beta   150.69
_cell_angle_gamma   41.93
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2SeBr
_chemical_formula_sum   'Mg2 Se1 Br1'
_cell_volume   107.89
_cell_formula_units_Z   1
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
  Mg  Mg1  1  0.0  0.0  0.0  1.0
  Mg  Mg2  1  0.94  0.0  0.58  1.0
  Se  Se3  1  0.0  0.0  0.16  1.0
  Br  Br0  1  0.0  0.94  0.58  1.0

data_Mg2SeBr
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.88
_cell_length_b   3.88
_cell_length_c   7.67
_cell_angle_alpha   104.65
_cell_angle_beta   104.65
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2SeBr
_chemical_formula_sum   'Mg2 Se1 Br1'
_cell_volume   107.89
_cell_formula_units_Z   1
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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.42  0.0  0.36  1.0
  Se  Se2  1  0.84  0.0  0.84  1.0
  Br  Br3  1  0.36  0.94  0.36  1.0

Mg Mg Se Br
Mg Mg Se Br 0 2 o o o 1 3 + - o 