data_[Tl2Ni1Se2]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Tl  1.6200  1.9000  1.3325
  Ni  1.9100  1.3500  0.7400
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [P4/mmm]
_cell_length_a [4.2654]
_cell_length_b [4.2654]
_cell_length_c [19.4688]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [123]
_chemical_formula_structural [Tl2NiSe2]
_chemical_formula_sum '[Tl2 Ni1 Se2]'
_cell_volume [354.2032]
_cell_formula_units_Z [1]
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
[
  Tl  Tl0  2  0.5000  0.5000  0.4174  1
  Ni  Ni1  1  0.0000  0.0000  0.5000  1
  Se  Se2  2  0.0000  0.0000  0.3852  1
]