data_Si2PbBr
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.34
_cell_length_b   5.08
_cell_length_c   5.58
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si2PbBr
_chemical_formula_sum   'Si2 Pb1 Br1'
_cell_volume   94.48
_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
  Si  Si2  1  0.0  0.0  0.0  1.0
  Si  Si3  1  0.67  0.54  0.0  1.0
  Pb  Pb1  1  0.0  0.54  0.79  1.0
  Br  Br0  1  0.67  0.0  0.79  1.0

data_Si2PbBr
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.34
_cell_length_b   5.08
_cell_length_c   5.58
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si2PbBr
_chemical_formula_sum   'Si2 Pb1 Br1'
_cell_volume   94.48
_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
  Si  Si0  1  0.0  0.0  0.0  1.0
  Si  Si1  1  0.67  0.54  0.0  1.0
  Pb  Pb2  1  0.0  0.54  0.79  1.0
  Br  Br3  1  0.67  0.0  0.79  1.0

Si Si Pb Br
Si Si Pb Br 0 3 - o - 1 2 + o - 