data_SiSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.63
_cell_length_b   3.63
_cell_length_c   11.81
_cell_angle_alpha   93.36
_cell_angle_beta   93.36
_cell_angle_gamma   58.39
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SiSe4
_chemical_formula_sum   'Si1 Se4'
_cell_volume   132.46
_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
  Si  Si4  1  0.0  0.0  0.0  1.0
  Se  Se0  1  0.23  0.0  0.42  1.0
  Se  Se1  1  0.32  0.0  0.36  1.0
  Se  Se2  1  0.36  0.0  0.09  1.0
  Se  Se3  1  0.19  0.0  0.69  1.0

data_SiSe4
_symmetry_space_group_name_H-M   Cm
_cell_length_a   3.63
_cell_length_b   6.19
_cell_length_c   11.81
_cell_angle_alpha   90.0
_cell_angle_beta   93.36
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   SiSe4
_chemical_formula_sum   'Si2 Se8'
_cell_volume   265.17
_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
  Si  Si0  2  0.0  0.0  0.0  1.0
  Se  Se1  2  0.14  0.5  0.91  1.0
  Se  Se2  2  0.18  0.5  0.64  1.0
  Se  Se3  2  0.27  0.5  0.58  1.0
  Se  Se4  2  0.31  0.5  0.31  1.0

Si Se Se Se Se