data_Ti2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.29
_cell_length_b   8.29
_cell_length_c   8.29
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ti2Se
_chemical_formula_sum   'Ti16 Se8'
_cell_volume   402.53
_cell_formula_units_Z   8
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
  Ti  Ti8  1  0.4  0.47  0.4  1.0
  Ti  Ti9  1  0.47  0.47  0.47  1.0
  Ti  Ti10  1  0.47  0.4  0.4  1.0
  Ti  Ti11  1  0.4  0.4  0.47  1.0
  Ti  Ti12  1  0.79  0.21  0.79  1.0
  Ti  Ti13  1  0.79  0.79  0.37  1.0
  Ti  Ti14  1  0.21  0.79  0.79  1.0
  Ti  Ti15  1  0.37  0.79  0.79  1.0
  Ti  Ti16  1  0.79  0.79  0.21  1.0
  Ti  Ti17  1  0.79  0.37  0.79  1.0
  Ti  Ti18  1  0.86  0.44  0.86  1.0
  Ti  Ti19  1  0.86  0.86  0.28  1.0
  Ti  Ti20  1  0.44  0.86  0.86  1.0
  Ti  Ti21  1  0.28  0.86  0.86  1.0
  Ti  Ti22  1  0.86  0.86  0.44  1.0
  Ti  Ti23  1  0.86  0.28  0.86  1.0
  Se  Se0  1  0.57  0.57  0.15  1.0
  Se  Se1  1  0.15  0.57  0.57  1.0
  Se  Se2  1  0.15  0.15  0.15  1.0
  Se  Se3  1  0.57  0.15  0.57  1.0
  Se  Se4  1  0.08  0.08  0.5  1.0
  Se  Se5  1  0.5  0.08  0.08  1.0
  Se  Se6  1  0.5  0.5  0.5  1.0
  Se  Se7  1  0.08  0.5  0.08  1.0

data_Ti2Se
_symmetry_space_group_name_H-M   R3m
_cell_length_a   8.29
_cell_length_b   8.29
_cell_length_c   20.3
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Ti2Se
_chemical_formula_sum   'Ti48 Se24'
_cell_volume   1207.58
_cell_formula_units_Z   24
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
  Ti  Ti0  9  0.02  0.05  0.58  1.0
  Ti  Ti1  9  0.05  0.53  0.74  1.0
  Ti  Ti2  9  0.05  0.53  0.67  1.0
  Ti  Ti3  9  0.19  0.38  0.95  1.0
  Ti  Ti4  9  0.19  0.38  0.02  1.0
  Ti  Ti5  3  0.0  0.0  0.53  1.0
  Se  Se6  9  0.05  0.52  0.45  1.0
  Se  Se7  9  0.19  0.38  0.23  1.0
  Se  Se8  3  0.0  0.0  0.5  1.0
  Se  Se9  3  0.0  0.0  0.85  1.0

Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Se Se Se Se Se Se Se Se
Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti Se Se Se Se Se Se Se Se 0 3 o o o 0 2 o o o 0 1 o o o 0 16 o o o 0 17 o o o 1 3 o o o 1 2 o o o 1 22 o o o 1 16 o o o 1 17 o o o 1 19 o o o 2 3 o o o 2 16 o o o 2 19 o o o 3 17 o o o 3 19 o o o 4 15 o o o 4 9 o o o 4 20 + o o 4 21 o o + 5 11 o o o 5 8 o o o 5 14 o o o 6 13 o o o 6 7 o o o 6 20 o + o 6 23 o o + 7 13 o o o 7 12 o o o 8 11 o o o 8 21 o + o 8 23 + o o 9 15 o o o 9 10 o o o 10 15 o o o 11 14 o o o 12 13 o o o 18 20 o o o 18 21 o o o 18 23 o o o 
Ti2Se crystallizes in the trigonal R3m space group. There are six inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 5-coordinate geometry to one Ti(2), two equivalent Ti(1), and two equivalent Se(1) atoms. The Ti(1)-Ti(2) bond length is 1.00 Å. Both Ti(1)-Ti(1) bond lengths are 0.58 Å. Both Ti(1)-Se(1) bond lengths are 1.93 Å. In the second Ti site, Ti(2) is bonded in a single-bond geometry to three equivalent Ti(1) and one Se(4) atom. The Ti(2)-Se(4) bond length is 0.81 Å. In the third Ti site, Ti(3) is bonded in a 6-coordinate geometry to one Ti(4), one Ti(6), one Se(1), one Se(4), and two equivalent Se(3) atoms. The Ti(3)-Ti(4) bond length is 1.27 Å. The Ti(3)-Ti(6) bond length is 1.42 Å. The Ti(3)-Se(1) bond length is 3.45 Å. The Ti(3)-Se(4) bond length is 3.35 Å. Both Ti(3)-Se(3) bond lengths are 2.63 Å. In the fourth Ti site, Ti(4) is bonded in a distorted single-bond geometry to one Ti(3), one Ti(5), and one Ti(6) atom. The Ti(4)-Ti(5) bond length is 1.42 Å. The Ti(4)-Ti(6) bond length is 0.83 Å. In the fifth Ti site, Ti(5) is bonded in a 6-coordinate geometry to one Ti(4), one Ti(6), one Se(2), one Se(3), and two equivalent Se(1) atoms. The Ti(5)-Ti(6) bond length is 1.27 Å. The Ti(5)-Se(2) bond length is 3.35 Å. The Ti(5)-Se(3) bond length is 3.45 Å. Both Ti(5)-Se(1) bond lengths are 2.63 Å. In the sixth Ti site, Ti(6) is bonded in a distorted single-bond geometry to one Ti(3), one Ti(4), and one Ti(5) atom. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Ti(3), two equivalent Ti(1), and two equivalent Ti(5) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to three equivalent Ti(5) and three equivalent Se(3) atoms. All Se(2)-Se(3) bond lengths are 2.53 Å. In the third Se site, Se(3) is bonded in a distorted L-shaped geometry to one Ti(5), two equivalent Ti(3), and one Se(2) atom. In the fourth Se site, Se(4) is bonded in a single-bond geometry to one Ti(2) and three equivalent Ti(3) atoms.