data_Mg2CuSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.95
_cell_length_b   5.58
_cell_length_c   7.94
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2CuSe2
_chemical_formula_sum   'Mg4 Cu2 Se4'
_cell_volume   219.28
_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  Mg2  1  0.47  0.79  0.23  1.0
  Mg  Mg3  1  0.0  0.0  0.71  1.0
  Mg  Mg4  1  0.47  0.0  0.5  1.0
  Mg  Mg5  1  0.0  0.79  0.44  1.0
  Cu  Cu0  1  0.47  0.79  0.83  1.0
  Cu  Cu1  1  0.0  0.0  0.11  1.0
  Se  Se6  1  0.47  0.79  0.46  1.0
  Se  Se7  1  0.0  0.0  0.48  1.0
  Se  Se8  1  0.47  0.0  0.11  1.0
  Se  Se9  1  0.0  0.79  0.83  1.0

data_Mg2CuSe2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   4.95
_cell_length_b   5.58
_cell_length_c   7.94
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   Mg2CuSe2
_chemical_formula_sum   'Mg4 Cu2 Se4'
_cell_volume   219.28
_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  0.24  0.4  0.76  1.0
  Mg  Mg1  2  0.24  0.6  0.03  1.0
  Cu  Cu2  2  0.24  0.4  0.36  1.0
  Se  Se3  2  0.24  0.4  0.99  1.0
  Se  Se4  2  0.24  0.6  0.64  1.0

Mg Mg Mg Mg Cu Cu Se Se Se Se