data_HgC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.44
_cell_length_b   7.44
_cell_length_c   5.8
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   159.78
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HgC2
_chemical_formula_sum   'Hg2 C4'
_cell_volume   110.85
_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
  Hg  Hg4  1  0.31  0.88  0.35  1.0
  Hg  Hg5  1  0.31  0.12  0.45  1.0
  C  C0  1  0.31  0.16  0.35  1.0
  C  C1  1  0.31  0.46  0.35  1.0
  C  C2  1  0.31  0.54  0.45  1.0
  C  C3  1  0.31  0.84  0.45  1.0

data_HgC2
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.61
_cell_length_b   5.8
_cell_length_c   7.44
_cell_angle_alpha   90.0
_cell_angle_beta   100.11
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   HgC2
_chemical_formula_sum   'Hg2 C4'
_cell_volume   110.85
_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
  Hg  Hg0  2  0.12  0.45  0.62  1.0
  C  C1  2  0.16  0.55  0.66  1.0
  C  C2  2  0.46  0.55  0.96  1.0

Hg Hg C C C C