data_[K8Cu4Se8]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  K  0.8200  2.2000  1.5200
  Cu  1.9000  1.3500  0.8200
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [C2/m]
_cell_length_a [12.5312]
_cell_length_b [4.0190]
_cell_length_c [12.1588]
_cell_angle_alpha [90.0000]
_cell_angle_beta [109.2866]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [12]
_chemical_formula_structural [K2CuSe2]
_chemical_formula_sum '[K8 Cu4 Se8]'
_cell_volume [577.9884]
_cell_formula_units_Z [4]
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
[
  K  K0  4  0.0850  0.0000  0.9092  1.0
  K  K1  4  0.1663  0.5000  0.6269  1.0
  Cu  Cu2  4  0.0971  0.5000  0.3011  1.0
  Se  Se3  4  0.0600  0.0000  0.3822  1.0
  Se  Se4  4  0.1662  0.5000  0.1488  1.0
]