data_Na2ZnSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.23
_cell_length_b   4.39
_cell_length_c   5.75
_cell_angle_alpha   90.0
_cell_angle_beta   103.83
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2ZnSe
_chemical_formula_sum   'Na2 Zn1 Se1'
_cell_volume   103.8
_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  0.97  0.2  0.06  1.0
  Na  Na1  1  0.73  0.0  0.85  1.0
  Zn  Zn3  1  0.02  0.0  0.37  1.0
  Se  Se2  1  0.42  0.2  0.69  1.0

data_Na2ZnSe
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.23
_cell_length_b   4.39
_cell_length_c   5.75
_cell_angle_alpha   90.0
_cell_angle_beta   103.83
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2ZnSe
_chemical_formula_sum   'Na2 Zn1 Se1'
_cell_volume   103.8
_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  0.73  0.0  0.85  1.0
  Na  Na1  1  0.97  0.2  0.06  1.0
  Zn  Zn2  1  0.02  0.0  0.37  1.0
  Se  Se3  1  0.42  0.2  0.69  1.0

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