data_NiSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.42
_cell_length_b   4.42
_cell_length_c   2.81
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NiSe2
_chemical_formula_sum   'Ni1 Se2'
_cell_volume   54.73
_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
  Ni  Ni0  1  0.0  0.0  0.0  1.0
  Se  Se1  1  0.0  0.21  0.4  1.0
  Se  Se2  1  0.21  0.0  0.4  1.0

data_NiSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.24
_cell_length_b   6.24
_cell_length_c   2.81
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NiSe2
_chemical_formula_sum   'Ni2 Se4'
_cell_volume   109.46
_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
  Ni  Ni0  2  0.0  0.0  0.0  1.0
  Se  Se1  4  0.1  0.1  0.4  1.0

Ni Se Se
Ni Se Se 0 2 o o o 0 1 o o o 1 2 o o o 