data_BaSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.22
_cell_length_b   6.22
_cell_length_c   6.22
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BaSe2
_chemical_formula_sum   'Ba2 Se4'
_cell_volume   170.1
_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
  Ba  Ba0  1  0.0  0.0  0.0  1.0
  Ba  Ba1  1  0.2  0.2  0.2  1.0
  Se  Se2  1  0.3  0.3  0.5  1.0
  Se  Se3  1  0.5  0.3  0.3  1.0
  Se  Se4  1  0.3  0.5  0.3  1.0
  Se  Se5  1  0.5  0.5  0.5  1.0

data_BaSe2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.22
_cell_length_b   6.22
_cell_length_c   15.23
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   BaSe2
_chemical_formula_sum   'Ba6 Se12'
_cell_volume   510.31
_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
  Ba  Ba0  3  0.0  0.0  0.0  1.0
  Ba  Ba1  3  0.0  0.0  0.8  1.0
  Se  Se2  9  0.07  0.13  0.64  1.0
  Se  Se3  3  0.0  0.0  0.5  1.0

Ba Ba Se Se Se Se
Ba Ba Se Se Se Se 0 3 - o o 0 4 o - o 0 2 o o - 0 1 o o o 1 4 o o o 1 3 o o o 1 2 o o o 2 4 o o o 2 3 o o o 2 5 o o o 3 4 o o o 3 5 o o o 4 5 o o o 
BaSe2 crystallizes in the trigonal R3m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted trigonal planar geometry to three equivalent Se(1) atoms. All Ba(1)-Se(1) bond lengths are 2.92 Å. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to three equivalent Se(1) and three equivalent Se(2) atoms. All Ba(2)-Se(1) bond lengths are 2.62 Å. All Ba(2)-Se(2) bond lengths are 3.63 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Se(2), and two equivalent Se(1) atoms. The Se(1)-Se(2) bond length is 2.14 Å. Both Se(1)-Se(1) bond lengths are 1.24 Å. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to three equivalent Ba(2) and three equivalent Se(1) atoms.