data_Si2Hg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.18
_cell_length_b   4.18
_cell_length_c   9.04
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si2Hg
_chemical_formula_sum   'Si4 Hg2'
_cell_volume   136.57
_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
  Si  Si2  1  0.09  0.21  0.45  1.0
  Si  Si3  1  0.0  0.41  0.97  1.0
  Si  Si4  1  0.09  0.21  0.07  1.0
  Si  Si5  1  0.0  0.41  0.59  1.0
  Hg  Hg0  1  0.0  0.0  0.52  1.0
  Hg  Hg1  1  0.0  0.0  0.0  1.0

data_Si2Hg
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.18
_cell_length_b   4.18
_cell_length_c   9.04
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si2Hg
_chemical_formula_sum   'Si4 Hg2'
_cell_volume   136.57
_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
  Si  Si0  1  0.0  0.41  0.59  1.0
  Si  Si1  1  0.0  0.41  0.97  1.0
  Si  Si2  1  0.09  0.21  0.07  1.0
  Si  Si3  1  0.09  0.21  0.45  1.0
  Hg  Hg4  1  0.0  0.0  0.0  1.0
  Hg  Hg5  1  0.0  0.0  0.52  1.0

Si Si Si Si Hg Hg
Si Si Si Si Hg Hg 0 4 o o o 0 3 o o o 1 5 o o + 1 2 o o + 2 5 o o o 3 4 o o o 