data_NaSi2Hg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.41
_cell_length_b   3.41
_cell_length_c   7.38
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaSi2Hg
_chemical_formula_sum   'Na1 Si2 Hg1'
_cell_volume   85.93
_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  Na1  1  0.0  0.0  0.63  1.0
  Si  Si2  1  0.71  0.71  0.64  1.0
  Si  Si3  1  0.0  0.0  0.26  1.0
  Hg  Hg0  1  0.71  0.71  0.54  1.0

data_NaSi2Hg
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.82
_cell_length_b   4.82
_cell_length_c   7.38
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaSi2Hg
_chemical_formula_sum   'Na2 Si4 Hg2'
_cell_volume   171.86
_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+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  0.0  0.63  1.0
  Si  Si1  2  0.0  0.0  0.26  1.0
  Si  Si2  2  0.21  0.5  0.64  1.0
  Hg  Hg3  2  0.21  0.5  0.54  1.0

Na Si Si Hg