data_[Si21Te18]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Si  1.9000  1.1000  0.5400
  Te  2.1000  1.4000  1.2933
]
_symmetry_space_group_name_H-M [R-3m]
_cell_length_a [5.9500]
_cell_length_b [5.9500]
_cell_length_c [31.1702]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [166]
_chemical_formula_structural [Si7Te6]
_chemical_formula_sum '[Si21 Te18]'
_cell_volume [955.6573]
_cell_formula_units_Z [3]
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
[
  Si  Si0  18  0.0502  0.5251  0.0931  1
  Si  Si1  3  -0.0000  -0.0000  0.5000  1
  Te  Te2  6  0.0000  0.0000  0.0693  1
  Te  Te3  6  0.0000  0.0000  0.1798  1
  Te  Te4  6  0.0000  0.0000  0.3029  1
]