data_Mg2Cu2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.72
_cell_length_b   6.72
_cell_length_c   3.81
_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   171.96
_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  0.11  0.47  0.9  1.0
  Mg  Mg5  1  0.62  0.26  0.9  1.0
  Mg  Mg6  1  0.26  0.11  0.9  1.0
  Mg  Mg7  1  0.47  0.62  0.9  1.0
  Cu  Cu0  1  0.5  0.86  0.0  1.0
  Cu  Cu1  1  0.22  0.86  0.0  1.0
  Cu  Cu2  1  0.86  0.5  0.0  1.0
  Cu  Cu3  1  0.86  0.22  0.0  1.0
  Se  Se8  1  0.0  0.0  0.0  1.0
  Se  Se9  1  0.36  0.36  0.0  1.0

data_Mg2Cu2Se
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.81
_cell_length_b   6.72
_cell_length_c   6.72
_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   171.96
_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  Mg0  1  0.9  0.11  0.47  1.0
  Mg  Mg1  1  0.9  0.26  0.11  1.0
  Mg  Mg2  1  0.9  0.47  0.62  1.0
  Mg  Mg3  1  0.9  0.62  0.26  1.0
  Cu  Cu4  1  0.0  0.86  0.5  1.0
  Cu  Cu5  1  0.0  0.86  0.22  1.0
  Cu  Cu6  1  0.0  0.22  0.86  1.0
  Cu  Cu7  1  0.0  0.5  0.86  1.0
  Se  Se8  1  0.0  0.0  0.0  1.0
  Se  Se9  1  0.0  0.36  0.36  1.0

Mg Mg Mg Mg Cu Cu Cu Cu Se Se
Mg Mg Mg Mg Cu Cu Cu Cu Se Se 0 6 - o + 0 9 o o + 1 9 o o + 1 7 o o + 2 8 o o + 2 5 o - + 2 9 o o + 3 9 o o + 3 4 o o + 4 5 o o o 5 8 o + o 6 7 o o o 7 8 + o o 