data_BaI3
_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   BaI3
_chemical_formula_sum   'Ba1 I3'
_cell_volume   162.95
_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
  Ba  Ba0  1  0.34  0.34  0.34  1.0
  I  I1  1  0.5  0.5  0.5  1.0
  I  I2  1  0.0  0.0  0.0  1.0
  I  I3  1  0.17  0.17  0.17  1.0

data_BaI3
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.13
_cell_length_b   6.13
_cell_length_c   15.02
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   BaI3
_chemical_formula_sum   'Ba3 I9'
_cell_volume   488.84
_cell_formula_units_Z   3
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  0.66  1.0
  I  I1  3  0.0  0.0  0.0  1.0
  I  I2  3  0.0  0.0  0.5  1.0
  I  I3  3  0.0  0.0  0.83  1.0

Ba I I I
BaI3 crystallizes in the trigonal R3m space group. Ba(1) is bonded to one I(1), one I(3), and three equivalent I(2) atoms to form distorted BaI5 trigonal bipyramids that share corners with six equivalent Ba(1)I5 trigonal bipyramids and  a cornercorner with one I(2)Ba3I trigonal pyramid. The Ba(1)-I(1) bond length is 2.52 Å. The Ba(1)-I(3) bond length is 2.52 Å. All Ba(1)-I(2) bond lengths are 3.54 Å. There are three inequivalent I sites. In the first I site, I(1) is bonded in a single-bond geometry to one Ba(1) atom. In the second I site, I(2) is bonded to three equivalent Ba(1) and one I(3) atom to form IBa3I trigonal pyramids that share  a cornercorner with one Ba(1)I5 trigonal bipyramid and corners with six equivalent I(2)Ba3I trigonal pyramids. The I(2)-I(3) bond length is 2.52 Å. In the third I site, I(3) is bonded in a single-bond geometry to one Ba(1) and one I(2) atom.