data_Na2NbTl
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.9
_cell_length_b   5.9
_cell_length_c   2.99
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2NbTl
_chemical_formula_sum   'Na2 Nb1 Tl1'
_cell_volume   103.93
_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
  Na  Na0  1  0.95  0.0  0.49  1.0
  Na  Na1  1  0.0  0.95  0.49  1.0
  Nb  Nb2  1  0.0  0.0  0.0  1.0
  Tl  Tl3  1  0.95  0.95  0.0  1.0

data_Na2NbTl
_symmetry_space_group_name_H-M   Amm2
_cell_length_a   2.99
_cell_length_b   8.34
_cell_length_c   8.34
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   38
_chemical_formula_structural   Na2NbTl
_chemical_formula_sum   'Na4 Nb2 Tl2'
_cell_volume   207.85
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, z'
  3  '-x, y, z'
  4  'x, -y, z'
  5  'x, y+1/2, z+1/2'
  6  '-x, -y+1/2, z+1/2'
  7  '-x, y+1/2, z+1/2'
  8  'x, -y+1/2, z+1/2'
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
  Na  Na0  4  0.5  0.03  0.97  1.0
  Nb  Nb1  2  0.0  0.0  0.0  1.0
  Tl  Tl2  2  0.0  0.0  0.95  1.0

Na Na Nb Tl
Na Na Nb Tl 0 1 + - o 2 3 - - o 