data_Mg2Cu2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.7
_cell_length_b   3.7
_cell_length_c   13.16
_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   180.11
_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  0.0  0.0  0.0  1.0
  Mg  Mg5  1  0.85  0.85  0.0  1.0
  Mg  Mg6  1  0.85  0.0  0.51  1.0
  Mg  Mg7  1  0.0  0.85  0.65  1.0
  Cu  Cu0  1  0.0  0.0  0.58  1.0
  Cu  Cu1  1  0.85  0.85  0.58  1.0
  Cu  Cu2  1  0.85  0.0  0.89  1.0
  Cu  Cu3  1  0.0  0.85  0.28  1.0
  Se  Se8  1  0.85  0.0  0.29  1.0
  Se  Se9  1  0.0  0.85  0.87  1.0

data_Mg2Cu2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.23
_cell_length_b   5.23
_cell_length_c   13.16
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2Cu2Se
_chemical_formula_sum   'Mg8 Cu8 Se4'
_cell_volume   360.22
_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  0.42  0.42  0.0  1.0
  Mg  Mg1  2  0.0  0.0  0.65  1.0
  Mg  Mg2  2  0.35  0.5  0.51  1.0
  Cu  Cu3  4  0.42  0.42  0.58  1.0
  Cu  Cu4  2  0.0  0.0  0.28  1.0
  Cu  Cu5  2  0.35  0.5  0.89  1.0
  Se  Se6  2  0.0  0.0  0.87  1.0
  Se  Se7  2  0.35  0.5  0.29  1.0

Mg Mg Mg Mg Cu Cu Cu Cu Se Se