data_[Mg2Cu4Se4]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Mg  1.3100  1.5000  0.8600
  Cu  1.9000  1.3500  0.8200
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [C2]
_cell_length_a [6.2042]
_cell_length_b [5.9243]
_cell_length_c [18.4083]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [5]
_chemical_formula_structural [Mg(CuSe)2]
_chemical_formula_sum '[Mg2 Cu4 Se4]'
_cell_volume [676.6134]
_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  2  0.0000  0.1180  0.0000  1
  Cu  Cu1  4  0.0697  0.6644  0.0622  1
  Se  Se2  4  0.2453  0.8451  0.9074  1
]