data_Na2NbHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.87
_cell_length_b   4.66
_cell_length_c   6.92
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2NbHg
_chemical_formula_sum   'Na2 Nb1 Hg1'
_cell_volume   92.73
_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  Na1  1  0.0  0.0  0.89  1.0
  Na  Na2  1  0.44  0.33  0.77  1.0
  Nb  Nb3  1  0.0  0.0  0.75  1.0
  Hg  Hg0  1  0.44  0.33  0.89  1.0

data_Na2NbHg
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.87
_cell_length_b   4.66
_cell_length_c   6.92
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2NbHg
_chemical_formula_sum   'Na2 Nb1 Hg1'
_cell_volume   92.73
_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  0.0  0.0  0.89  1.0
  Na  Na1  1  0.44  0.33  0.77  1.0
  Nb  Nb2  1  0.0  0.0  0.75  1.0
  Hg  Hg3  1  0.44  0.33  0.89  1.0

Na Na Nb Hg
Na Na Nb Hg 0 2 o o o 1 3 o o o 