data_Mg2Cu2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.68
_cell_length_b   4.05
_cell_length_c   12.21
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Cu2Se
_chemical_formula_sum   'Mg4 Cu4 Se2'
_cell_volume   182.16
_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
  Mg  Mg4  1  0.84  0.03  0.01  1.0
  Mg  Mg5  1  0.0  0.0  0.2  1.0
  Mg  Mg6  1  0.0  0.0  0.83  1.0
  Mg  Mg7  1  0.84  0.03  0.38  1.0
  Cu  Cu0  1  0.0  0.03  0.29  1.0
  Cu  Cu1  1  0.84  0.0  0.92  1.0
  Cu  Cu2  1  0.84  0.0  0.06  1.0
  Cu  Cu3  1  0.0  0.03  0.16  1.0
  Se  Se8  1  0.84  0.03  0.31  1.0
  Se  Se9  1  0.0  0.0  0.9  1.0

data_Mg2Cu2Se
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.68
_cell_length_b   4.05
_cell_length_c   12.21
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   Mg2Cu2Se
_chemical_formula_sum   'Mg4 Cu4 Se2'
_cell_volume   182.16
_cell_formula_units_Z   2
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
  Mg  Mg0  2  0.42  0.01  0.27  1.0
  Mg  Mg1  2  0.42  0.01  0.91  1.0
  Cu  Cu2  2  0.42  0.99  0.81  1.0
  Cu  Cu3  2  0.42  0.99  0.95  1.0
  Se  Se4  2  0.42  0.01  0.2  1.0

Mg Mg Mg Mg Cu Cu Cu Cu Se Se