data_NaHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.86
_cell_length_b   5.86
_cell_length_c   5.47
_cell_angle_alpha   102.82
_cell_angle_beta   102.82
_cell_angle_gamma   35.46
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaHg
_chemical_formula_sum   'Na2 Hg2'
_cell_volume   106.14
_cell_formula_units_Z   2
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  Na2  1  0.05  0.0  0.51  1.0
  Na  Na3  1  0.85  0.0  0.82  1.0
  Hg  Hg0  1  0.94  0.0  0.56  1.0
  Hg  Hg1  1  0.95  0.0  0.76  1.0

data_NaHg
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.57
_cell_length_b   5.47
_cell_length_c   5.86
_cell_angle_alpha   102.82
_cell_angle_beta   107.73
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   NaHg
_chemical_formula_sum   'Na2 Hg2'
_cell_volume   106.14
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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  2  0.0  0.35  0.6  1.0
  Hg  Hg1  2  0.0  0.4  0.49  1.0

Na Na Hg Hg
Na Na Hg Hg 0 2 - o o 1 3 o o o 