data_BiSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.76
_cell_length_b   3.76
_cell_length_c   8.05
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   91.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BiSe
_chemical_formula_sum   'Bi2 Se2'
_cell_volume   114.02
_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
  Bi  Bi0  1  0.64  0.34  0.33  1.0
  Bi  Bi1  1  0.64  0.66  0.72  1.0
  Se  Se2  1  0.64  0.34  0.42  1.0
  Se  Se3  1  0.64  0.66  0.64  1.0

data_BiSe
_symmetry_space_group_name_H-M   P2/m
_cell_length_a   3.76
_cell_length_b   3.76
_cell_length_c   8.05
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   10
_chemical_formula_structural   BiSe
_chemical_formula_sum   'Bi2 Se2'
_cell_volume   114.04
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-x, y, -z'
  4  '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
  Bi  Bi0  2  0.34  0.0  0.3  1.0
  Se  Se1  2  0.34  0.0  0.39  1.0

Bi Bi Se Se
Bi Bi Se Se 0 2 o o o 1 3 o o o 