data_Na2SiHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.57
_cell_length_b   5.57
_cell_length_c   5.57
_cell_angle_alpha   134.77
_cell_angle_beta   132.98
_cell_angle_gamma   67.29
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2SiHg
_chemical_formula_sum   'Na2 Si1 Hg1'
_cell_volume   88.42
_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  0.22  0.35  1.0
  Na  Na2  1  0.14  0.0  0.29  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0
  Hg  Hg0  1  0.0  0.0  0.64  1.0

data_Na2SiHg
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.29
_cell_length_b   4.45
_cell_length_c   5.57
_cell_angle_alpha   113.51
_cell_angle_beta   112.61
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2SiHg
_chemical_formula_sum   'Na2 Si1 Hg1'
_cell_volume   88.42
_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  0.65  0.87  0.87  1.0
  Na  Na1  1  0.85  0.71  0.85  1.0
  Si  Si2  1  0.0  0.0  0.0  1.0
  Hg  Hg3  1  0.36  0.36  0.36  1.0

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