data_[Si3Se3]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Si  1.9000  1.1000  0.5400
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [P4/mmm]
_cell_length_a [5.2768]
_cell_length_b [5.2768]
_cell_length_c [5.1647]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [123]
_chemical_formula_structural [SiSe]
_chemical_formula_sum '[Si3 Se3]'
_cell_volume [143.8069]
_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  2  0.0000  0.5000  0.0000  1
  Si  Si1  1  0.5000  0.5000  0.5000  1
  Se  Se2  2  0.0000  0.5000  0.5000  1
  Se  Se3  1  0.5000  0.5000  0.0000  1
]