data_[K2Na2Cu2Si8O20]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  K  0.8200  2.2000  1.5200
  Na  0.9300  1.8000  1.1600
  Cu  1.9000  1.3500  0.8200
  Si  1.9000  1.1000  0.5400
  O  3.4400  0.6000  1.2600
]
_symmetry_space_group_name_H-M [P-1]
_cell_length_a [6.9572]
_cell_length_b [7.8676]
_cell_length_c [9.7260]
_cell_angle_alpha [104.7101]
_cell_angle_beta [99.2321]
_cell_angle_gamma [114.7507]
_symmetry_Int_Tables_number [2]
_chemical_formula_structural [KNaCu(Si2O5)2]
_chemical_formula_sum '[K2 Na2 Cu2 Si8 O20]'
_cell_volume [445.5382]
_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
[
  K  K0  2  0.3329  0.2103  0.0037  1
  Na  Na1  2  0.3376  0.8704  0.5910  1
  Si  Si2  2  0.0450  0.7221  0.7856  1
  Si  Si3  2  0.1548  0.3872  0.7214  1
  Cu  Cu4  2  0.1634  0.1270  0.4128  1
  Si  Si5  2  0.1918  0.8304  0.1407  1
  Si  Si6  2  0.4364  0.6482  0.2810  1
  O  O7  2  0.0255  0.2095  0.5632  1
  O  O8  2  0.0432  0.3372  0.8527  1
  O  O9  2  0.0927  0.9072  0.7310  1
  O  O10  2  0.1457  0.8214  0.9683  1
  O  O11  2  0.1803  0.6060  0.7217  1
  O  O12  2  0.2158  0.4447  0.2631  1
  O  O13  2  0.2896  0.0556  0.2520  1
  O  O14  2  0.3730  0.7490  0.1636  1
  O  O15  2  0.4096  0.4343  0.7932  1
  O  O16  2  0.4444  0.1919  0.5530  1
]