data_Sb2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.13
_cell_length_b   6.13
_cell_length_c   6.13
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sb2Se
_chemical_formula_sum   'Sb4 Se2'
_cell_volume   162.7
_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
  Sb  Sb0  1  0.25  0.25  0.42  1.0
  Sb  Sb1  1  0.42  0.25  0.25  1.0
  Sb  Sb2  1  0.25  0.42  0.25  1.0
  Sb  Sb3  1  0.42  0.42  0.42  1.0
  Se  Se4  1  0.0  0.0  0.0  1.0
  Se  Se5  1  0.17  0.17  0.17  1.0

data_Sb2Se
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.13
_cell_length_b   6.13
_cell_length_c   15.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Sb2Se
_chemical_formula_sum   'Sb12 Se6'
_cell_volume   488.09
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Sb  Sb0  9  0.06  0.11  0.69  1.0
  Sb  Sb1  3  0.0  0.0  0.58  1.0
  Se  Se2  3  0.0  0.0  0.0  1.0
  Se  Se3  3  0.0  0.0  0.83  1.0

Sb Sb Sb Sb Se Se
Sb2Se crystallizes in the trigonal R3m space group. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 5-coordinate geometry to one Sb(2), two equivalent Sb(1), one Se(1), and one Se(2) atom. The Sb(1)-Sb(2) bond length is 1.77 Å. Both Sb(1)-Sb(1) bond lengths are 1.02 Å. The Sb(1)-Se(1) bond length is 2.98 Å. The Sb(1)-Se(2) bond length is 2.16 Å. In the second Sb site, Sb(2) is bonded in a 3-coordinate geometry to three equivalent Sb(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal pyramidal geometry to three equivalent Sb(1) and one Se(2) atom. The Se(1)-Se(2) bond length is 2.50 Å. In the second Se site, Se(2) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Sb(1) and one Se(1) atom.