data_HgC4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.14
_cell_length_b   6.14
_cell_length_c   6.14
_cell_angle_alpha   151.32
_cell_angle_beta   151.32
_cell_angle_gamma   41.01
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HgC4
_chemical_formula_sum   'Hg1 C4'
_cell_volume   53.22
_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
  Hg  Hg4  1  0.0  0.0  0.0  1.0
  C  C0  1  0.52  0.0  0.88  1.0
  C  C1  1  0.0  0.52  0.88  1.0
  C  C2  1  0.0  0.0  0.31  1.0
  C  C3  1  0.0  0.0  0.19  1.0

data_HgC4
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.3
_cell_length_b   4.3
_cell_length_c   6.14
_cell_angle_alpha   90.0
_cell_angle_beta   110.51
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HgC4
_chemical_formula_sum   'Hg2 C8'
_cell_volume   106.45
_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
  Hg  Hg0  2  0.0  0.0  0.0  1.0
  C  C1  4  0.26  0.26  0.65  1.0
  C  C2  2  0.0  0.0  0.69  1.0
  C  C3  2  0.0  0.0  0.81  1.0

Hg C C C C
Hg C C C C 0 4 o o o 1 3 o o o 1 3 + o + 1 4 + o + 2 4 o + + 2 3 o + + 2 3 o o o 3 4 o o o 