data_HgAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.28
_cell_length_b   3.28
_cell_length_c   10.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   115.29
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HgAs
_chemical_formula_sum   'Hg2 As2'
_cell_volume   105.71
_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  Hg2  1  0.76  0.39  0.93  1.0
  Hg  Hg3  1  0.76  0.61  0.93  1.0
  As  As0  1  0.76  0.39  0.88  1.0
  As  As1  1  0.76  0.61  0.99  1.0

data_HgAs
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.28
_cell_length_b   3.28
_cell_length_c   10.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   115.29
_symmetry_Int_Tables_number   2
_chemical_formula_structural   HgAs
_chemical_formula_sum   'Hg2 As2'
_cell_volume   105.71
_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  0.5  0.39  0.5  1.0
  As  As1  2  0.5  0.39  0.44  1.0

Hg Hg As As
Hg Hg As As 0 1 o o o 0 2 o o o 1 3 o o o 