data_NaPbSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.1
_cell_length_b   5.1
_cell_length_c   5.1
_cell_angle_alpha   113.58
_cell_angle_beta   113.58
_cell_angle_gamma   101.54
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaPbSe2
_chemical_formula_sum   'Na1 Pb1 Se2'
_cell_volume   100.85
_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
  Na  Na0  1  0.0  0.0  0.0  1.0
  Pb  Pb1  1  0.0  0.0  0.23  1.0
  Se  Se2  1  0.79  0.0  0.61  1.0
  Se  Se3  1  0.0  0.79  0.61  1.0

data_NaPbSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.45
_cell_length_b   7.91
_cell_length_c   5.1
_cell_angle_alpha   90.0
_cell_angle_beta   129.23
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaPbSe2
_chemical_formula_sum   'Na2 Pb2 Se4'
_cell_volume   201.7
_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+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
  Na  Na0  2  0.0  0.0  0.0  1.0
  Pb  Pb1  2  0.27  0.5  0.77  1.0
  Se  Se2  4  0.28  0.1  0.39  1.0

Na Pb Se Se
Na Pb Se Se 0 1 o o o 0 2 - o - 0 3 o - - 2 3 + - o 