data_PbSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.09
_cell_length_b   4.37
_cell_length_c   4.4
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   PbSe
_chemical_formula_sum   'Pb4 Se4'
_cell_volume   232.42
_cell_formula_units_Z   4
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
  Pb  Pb0  1  0.53  0.28  0.63  1.0
  Pb  Pb1  1  0.58  0.28  0.97  1.0
  Pb  Pb2  1  0.52  0.09  0.43  1.0
  Pb  Pb3  1  0.56  0.09  0.77  1.0
  Se  Se4  1  0.39  0.28  0.46  1.0
  Se  Se5  1  0.44  0.28  0.14  1.0
  Se  Se6  1  0.65  0.09  0.26  1.0
  Se  Se7  1  0.7  0.09  0.94  1.0

data_PbSe
_symmetry_space_group_name_H-M   P-1
_cell_length_a   4.37
_cell_length_b   4.4
_cell_length_c   12.09
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   PbSe
_chemical_formula_sum   'Pb4 Se4'
_cell_volume   232.42
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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
  Pb  Pb0  2  0.09  0.43  0.48  1.0
  Pb  Pb1  2  0.09  0.77  0.53  1.0
  Se  Se2  2  0.09  0.26  0.35  1.0
  Se  Se3  2  0.09  0.94  0.39  1.0

Pb Pb Pb Pb Se Se Se Se
Pb Pb Pb Pb Se Se Se Se 0 2 o o o 0 3 o o o 1 3 o o o 1 6 o o + 1 7 o o o 2 4 o o o 2 5 o o o 4 5 o o o 6 7 o o - 