The crystal structure described by Tm2Se3 crystallizes in the tetragonal I-42d space group. There are three inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 8-coordinate geometry to two equivalent Se(2), three equivalent Se(1), and three equivalent Se(3) atoms. In the second Tm site, Tm(2) is bonded in a 8-coordinate geometry to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. In the third Tm site, Tm(3) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(3), and four equivalent Se(2) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Tm(3), two equivalent Tm(2), and three equivalent Tm(1) atoms to form distorted SeTm6 octahedra that share corners with three equivalent Se(1)Tm6 octahedra, corners with seven equivalent Se(3)Tm5 square pyramids, corners with five equivalent Se(2)Tm5 trigonal bipyramids, edges with two equivalent Se(1)Tm6 octahedra,  an edgeedge with one Se(3)Tm5 square pyramid, edges with three equivalent Se(2)Tm5 trigonal bipyramids, faces with two equivalent Se(1)Tm6 octahedra, faces with two equivalent Se(3)Tm5 square pyramids, and  a faceface with one Se(2)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 20-48°. In the second Se site, Se(2) is bonded to one Tm(2), two equivalent Tm(1), and two equivalent Tm(3) atoms to form distorted SeTm5 trigonal bipyramids that share corners with five equivalent Se(1)Tm6 octahedra, corners with four equivalent Se(3)Tm5 square pyramids, corners with four equivalent Se(2)Tm5 trigonal bipyramids, edges with three equivalent Se(1)Tm6 octahedra, edges with four equivalent Se(3)Tm5 square pyramids,  an edgeedge with one Se(2)Tm5 trigonal bipyramid,  a faceface with one Se(1)Tm6 octahedra, and  a faceface with one Se(2)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 25-50°. In the third Se site, Se(3) is bonded to one Tm(2), one Tm(3), and three equivalent Tm(1) atoms to form distorted SeTm5 square pyramids that share corners with seven equivalent Se(1)Tm6 octahedra, corners with five equivalent Se(3)Tm5 square pyramids, corners with four equivalent Se(2)Tm5 trigonal bipyramids,  an edgeedge with one Se(1)Tm6 octahedra, edges with four equivalent Se(2)Tm5 trigonal bipyramids, faces with two equivalent Se(1)Tm6 octahedra, and  a faceface with one Se(3)Tm5 square pyramid. The corner-sharing octahedral tilt angles range from 16-54°. is represented by the CIF card [CIF]
data_Tm2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.285
_cell_length_b   14.285
_cell_length_c   14.285
_cell_angle_alpha   144.925
_cell_angle_beta   144.925
_cell_angle_gamma   50.447
_symmetry_Int_Tables_number   1
_cell_volume   957.870
_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
  Tm  Tm0  1  0.846  0.950  0.374  1.0
  Tm  Tm1  1  0.577  0.472  0.626  1.0
  Tm  Tm2  1  0.165  0.165  0.000  1.0
  Tm  Tm3  1  0.875  0.511  0.136  1.0
  Tm  Tm4  1  0.173  0.300  0.396  1.0
  Tm  Tm5  1  0.585  0.085  0.500  1.0
  Tm  Tm6  1  0.375  0.739  0.864  1.0
  Tm  Tm7  1  0.904  0.778  0.604  1.0
  Tm  Tm8  1  0.222  0.827  0.126  1.0
  Tm  Tm9  1  0.489  0.625  0.364  1.0
  Tm  Tm10  1  0.915  0.415  0.500  1.0
  Tm  Tm11  1  0.261  0.125  0.636  1.0
  Tm  Tm12  1  0.700  0.096  0.874  1.0
  Tm  Tm13  1  0.835  0.835  0.000  1.0
  Tm  Tm14  1  0.528  0.154  0.104  1.0
  Tm  Tm15  1  0.050  0.423  0.896  1.0
  Se  Se16  1  0.503  0.122  0.256  1.0
  Se  Se17  1  0.075  0.828  0.615  1.0
  Se  Se18  1  0.866  0.247  0.744  1.0
  Se  Se19  1  0.884  0.128  0.881  1.0
  Se  Se20  1  0.247  0.003  0.119  1.0
  Se  Se21  1  0.675  0.790  0.252  1.0
  Se  Se22  1  0.212  0.460  0.385  1.0
  Se  Se23  1  0.839  0.439  0.242  1.0
  Se  Se24  1  0.538  0.422  0.748  1.0
  Se  Se25  1  0.403  0.161  0.600  1.0
  Se  Se26  1  0.196  0.597  0.758  1.0
  Se  Se27  1  0.210  0.462  0.885  1.0
  Se  Se28  1  0.578  0.325  0.115  1.0
  Se  Se29  1  0.997  0.116  0.244  1.0
  Se  Se30  1  0.561  0.804  0.400  1.0
  Se  Se31  1  0.172  0.788  0.248  1.0
  Se  Se32  1  0.872  0.753  0.756  1.0
  Se  Se33  1  0.753  0.497  0.619  1.0
  Se  Se34  1  0.540  0.925  0.752  1.0
  Se  Se35  1  0.554  0.811  0.900  1.0
  Se  Se36  1  0.911  0.653  0.100  1.0
  Se  Se37  1  0.878  0.134  0.381  1.0
  Se  Se38  1  0.347  0.446  0.258  1.0
  Se  Se39  1  0.189  0.089  0.742  1.0
[/CIF]
.
The crystal structure described by Tm2Se3 crystallizes in the tetragonal I-42d space group. There are three inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 8-coordinate geometry to two equivalent Se(2), three equivalent Se(1), and three equivalent Se(3) atoms. In the second Tm site, Tm(2) is bonded in a 8-coordinate geometry to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. In the third Tm site, Tm(3) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(3), and four equivalent Se(2) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Tm(3), two equivalent Tm(2), and three equivalent Tm(1) atoms to form distorted SeTm6 octahedra that share corners with three equivalent Se(1)Tm6 octahedra, corners with seven equivalent Se(3)Tm5 square pyramids, corners with five equivalent Se(2)Tm5 trigonal bipyramids, edges with two equivalent Se(1)Tm6 octahedra,  an edgeedge with one Se(3)Tm5 square pyramid, edges with three equivalent Se(2)Tm5 trigonal bipyramids, faces with two equivalent Se(1)Tm6 octahedra, faces with two equivalent Se(3)Tm5 square pyramids, and  a faceface with one Se(2)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 20-48°. In the second Se site, Se(2) is bonded to one Tm(2), two equivalent Tm(1), and two equivalent Tm(3) atoms to form distorted SeTm5 trigonal bipyramids that share corners with five equivalent Se(1)Tm6 octahedra, corners with four equivalent Se(3)Tm5 square pyramids, corners with four equivalent Se(2)Tm5 trigonal bipyramids, edges with three equivalent Se(1)Tm6 octahedra, edges with four equivalent Se(3)Tm5 square pyramids,  an edgeedge with one Se(2)Tm5 trigonal bipyramid,  a faceface with one Se(1)Tm6 octahedra, and  a faceface with one Se(2)Tm5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 25-50°. In the third Se site, Se(3) is bonded to one Tm(2), one Tm(3), and three equivalent Tm(1) atoms to form distorted SeTm5 square pyramids that share corners with seven equivalent Se(1)Tm6 octahedra, corners with five equivalent Se(3)Tm5 square pyramids, corners with four equivalent Se(2)Tm5 trigonal bipyramids,  an edgeedge with one Se(1)Tm6 octahedra, edges with four equivalent Se(2)Tm5 trigonal bipyramids, faces with two equivalent Se(1)Tm6 octahedra, and  a faceface with one Se(3)Tm5 square pyramid. The corner-sharing octahedral tilt angles range from 16-54°. is represented by the CIF card [CIF]
data_Tm2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.285
_cell_length_b   14.285
_cell_length_c   14.285
_cell_angle_alpha   144.925
_cell_angle_beta   144.925
_cell_angle_gamma   50.447
_symmetry_Int_Tables_number   1
_cell_volume   957.870
_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
  Tm  Tm0  1  0.846  0.950  0.374  1.0
  Tm  Tm1  1  0.577  0.472  0.626  1.0
  Tm  Tm2  1  0.165  0.165  0.000  1.0
  Tm  Tm3  1  0.875  0.511  0.136  1.0
  Tm  Tm4  1  0.173  0.300  0.396  1.0
  Tm  Tm5  1  0.585  0.085  0.500  1.0
  Tm  Tm6  1  0.375  0.739  0.864  1.0
  Tm  Tm7  1  0.904  0.778  0.604  1.0
  Tm  Tm8  1  0.222  0.827  0.126  1.0
  Tm  Tm9  1  0.489  0.625  0.364  1.0
  Tm  Tm10  1  0.915  0.415  0.500  1.0
  Tm  Tm11  1  0.261  0.125  0.636  1.0
  Tm  Tm12  1  0.700  0.096  0.874  1.0
  Tm  Tm13  1  0.835  0.835  0.000  1.0
  Tm  Tm14  1  0.528  0.154  0.104  1.0
  Tm  Tm15  1  0.050  0.423  0.896  1.0
  Se  Se16  1  0.503  0.122  0.256  1.0
  Se  Se17  1  0.075  0.828  0.615  1.0
  Se  Se18  1  0.866  0.247  0.744  1.0
  Se  Se19  1  0.884  0.128  0.881  1.0
  Se  Se20  1  0.247  0.003  0.119  1.0
  Se  Se21  1  0.675  0.790  0.252  1.0
  Se  Se22  1  0.212  0.460  0.385  1.0
  Se  Se23  1  0.839  0.439  0.242  1.0
  Se  Se24  1  0.538  0.422  0.748  1.0
  Se  Se25  1  0.403  0.161  0.600  1.0
  Se  Se26  1  0.196  0.597  0.758  1.0
  Se  Se27  1  0.210  0.462  0.885  1.0
  Se  Se28  1  0.578  0.325  0.115  1.0
  Se  Se29  1  0.997  0.116  0.244  1.0
  Se  Se30  1  0.561  0.804  0.400  1.0
  Se  Se31  1  0.172  0.788  0.248  1.0
  Se  Se32  1  0.872  0.753  0.756  1.0
  Se  Se33  1  0.753  0.497  0.619  1.0
  Se  Se34  1  0.540  0.925  0.752  1.0
  Se  Se35  1  0.554  0.811  0.900  1.0
  Se  Se36  1  0.911  0.653  0.100  1.0
  Se  Se37  1  0.878  0.134  0.381  1.0
  Se  Se38  1  0.347  0.446  0.258  1.0
  Se  Se39  1  0.189  0.089  0.742  1.0
[/CIF]
.