data_Mg2CuSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.94
_cell_length_b   3.94
_cell_length_c   10.75
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2CuSe
_chemical_formula_sum   'Mg4 Cu2 Se2'
_cell_volume   167.12
_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  0.97  0.0  0.4  1.0
  Mg  Mg3  1  0.0  0.97  0.35  1.0
  Mg  Mg4  1  0.0  0.0  0.0  1.0
  Mg  Mg5  1  0.97  0.97  0.0  1.0
  Cu  Cu0  1  0.97  0.0  0.93  1.0
  Cu  Cu1  1  0.0  0.97  0.83  1.0
  Se  Se6  1  0.97  0.0  0.78  1.0
  Se  Se7  1  0.0  0.97  0.97  1.0

data_Mg2CuSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.57
_cell_length_b   5.57
_cell_length_c   10.75
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2CuSe
_chemical_formula_sum   'Mg8 Cu4 Se4'
_cell_volume   334.24
_cell_formula_units_Z   4
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
  Mg  Mg0  4  0.49  0.49  0.0  1.0
  Mg  Mg1  2  0.0  0.0  0.35  1.0
  Mg  Mg2  2  0.47  0.5  0.4  1.0
  Cu  Cu3  2  0.0  0.0  0.83  1.0
  Cu  Cu4  2  0.47  0.5  0.93  1.0
  Se  Se5  2  0.0  0.0  0.97  1.0
  Se  Se6  2  0.47  0.5  0.78  1.0

Mg Mg Mg Mg Cu Cu Se Se