The structure described by La2Se3 crystallizes in the tetragonal I-42d space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. In the second La site, La(2) is bonded to two equivalent Se(1), two equivalent Se(3), and four equivalent Se(2) atoms to form a mixture of distorted corner, edge, and face-sharing LaSe8 hexagonal bipyramids. In the third La site, La(3) is bonded to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms to form a mixture of distorted corner, edge, and face-sharing LaSe8 hexagonal bipyramids. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one La(2), two equivalent La(1), and two equivalent La(3) atoms to form SeLa5 trigonal bipyramids that share corners with five equivalent Se(2)La6 octahedra, corners with four equivalent Se(3)La5 square pyramids, corners with four equivalent Se(1)La5 trigonal bipyramids, edges with three equivalent Se(2)La6 octahedra, edges with four equivalent Se(3)La5 square pyramids,  an edgeedge with one Se(1)La5 trigonal bipyramid,  a faceface with one Se(2)La6 octahedra, and  a faceface with one Se(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-50°. In the second Se site, Se(2) is bonded to one La(3), two equivalent La(2), and three equivalent La(1) atoms to form distorted SeLa6 octahedra that share corners with three equivalent Se(2)La6 octahedra, corners with seven equivalent Se(3)La5 square pyramids, corners with five equivalent Se(1)La5 trigonal bipyramids, edges with two equivalent Se(2)La6 octahedra,  an edgeedge with one Se(3)La5 square pyramid, edges with three equivalent Se(1)La5 trigonal bipyramids, faces with two equivalent Se(2)La6 octahedra, faces with two equivalent Se(3)La5 square pyramids, and  a faceface with one Se(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 18-49°. In the third Se site, Se(3) is bonded to one La(2), one La(3), and three equivalent La(1) atoms to form distorted SeLa5 square pyramids that share corners with seven equivalent Se(2)La6 octahedra, corners with five equivalent Se(3)La5 square pyramids, corners with four equivalent Se(1)La5 trigonal bipyramids,  an edgeedge with one Se(2)La6 octahedra, edges with four equivalent Se(1)La5 trigonal bipyramids, faces with two equivalent Se(2)La6 octahedra, and  a faceface with one Se(3)La5 square pyramid. The corner-sharing octahedral tilt angles range from 13-54°. is represented by the CIF card [CIF]
data_La2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   15.075
_cell_length_b   15.075
_cell_length_c   15.076
_cell_angle_alpha   144.828
_cell_angle_beta   144.830
_cell_angle_gamma   50.590
_symmetry_Int_Tables_number   1
_cell_volume   1131.047
_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
  La  La0  1  0.202  0.323  0.604  1.0
  La  La1  1  0.416  0.916  0.500  1.0
  La  La2  1  0.995  0.625  0.870  1.0
  La  La3  1  0.334  0.334  0.000  1.0
  La  La4  1  0.031  0.927  0.379  1.0
  La  La5  1  0.755  0.125  0.130  1.0
  La  La6  1  0.548  0.651  0.621  1.0
  La  La7  1  0.349  0.969  0.896  1.0
  La  La8  1  0.375  0.245  0.370  1.0
  La  La9  1  0.666  0.666  1.000  1.0
  La  La10  1  0.875  0.005  0.630  1.0
  La  La11  1  0.073  0.453  0.104  1.0
  La  La12  1  0.084  0.584  0.500  1.0
  La  La13  1  0.677  0.281  0.879  1.0
  La  La14  1  0.719  0.598  0.396  1.0
  La  La15  1  0.402  0.798  0.121  1.0
  Se  Se16  1  0.713  0.823  0.746  1.0
  Se  Se17  1  0.363  0.610  0.106  1.0
  Se  Se18  1  0.504  0.257  0.894  1.0
  Se  Se19  1  0.246  0.640  0.253  1.0
  Se  Se20  1  0.387  0.993  0.747  1.0
  Se  Se21  1  0.077  0.968  0.254  1.0
  Se  Se22  1  0.673  0.427  0.390  1.0
  Se  Se23  1  0.037  0.283  0.610  1.0
  Se  Se24  1  0.062  0.154  0.749  1.0
  Se  Se25  1  0.687  0.938  0.092  1.0
  Se  Se26  1  0.573  0.963  0.246  1.0
  Se  Se27  1  0.846  0.595  0.908  1.0
  Se  Se28  1  0.717  0.327  0.754  1.0
  Se  Se29  1  0.007  0.754  0.394  1.0
  Se  Se30  1  0.405  0.313  0.251  1.0
  Se  Se31  1  0.360  0.613  0.606  1.0
  Se  Se32  1  0.390  0.496  0.753  1.0
  Se  Se33  1  0.032  0.287  0.109  1.0
  Se  Se34  1  0.904  0.312  0.249  1.0
  Se  Se35  1  0.177  0.923  0.891  1.0
  Se  Se36  1  0.063  0.655  0.751  1.0
  Se  Se37  1  0.743  0.637  0.247  1.0
  Se  Se38  1  0.345  0.096  0.408  1.0
  Se  Se39  1  0.688  0.937  0.592  1.0
[/CIF]
.
The structure described by La2Se3 crystallizes in the tetragonal I-42d space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. In the second La site, La(2) is bonded to two equivalent Se(1), two equivalent Se(3), and four equivalent Se(2) atoms to form a mixture of distorted corner, edge, and face-sharing LaSe8 hexagonal bipyramids. In the third La site, La(3) is bonded to two equivalent Se(2), two equivalent Se(3), and four equivalent Se(1) atoms to form a mixture of distorted corner, edge, and face-sharing LaSe8 hexagonal bipyramids. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one La(2), two equivalent La(1), and two equivalent La(3) atoms to form SeLa5 trigonal bipyramids that share corners with five equivalent Se(2)La6 octahedra, corners with four equivalent Se(3)La5 square pyramids, corners with four equivalent Se(1)La5 trigonal bipyramids, edges with three equivalent Se(2)La6 octahedra, edges with four equivalent Se(3)La5 square pyramids,  an edgeedge with one Se(1)La5 trigonal bipyramid,  a faceface with one Se(2)La6 octahedra, and  a faceface with one Se(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-50°. In the second Se site, Se(2) is bonded to one La(3), two equivalent La(2), and three equivalent La(1) atoms to form distorted SeLa6 octahedra that share corners with three equivalent Se(2)La6 octahedra, corners with seven equivalent Se(3)La5 square pyramids, corners with five equivalent Se(1)La5 trigonal bipyramids, edges with two equivalent Se(2)La6 octahedra,  an edgeedge with one Se(3)La5 square pyramid, edges with three equivalent Se(1)La5 trigonal bipyramids, faces with two equivalent Se(2)La6 octahedra, faces with two equivalent Se(3)La5 square pyramids, and  a faceface with one Se(1)La5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 18-49°. In the third Se site, Se(3) is bonded to one La(2), one La(3), and three equivalent La(1) atoms to form distorted SeLa5 square pyramids that share corners with seven equivalent Se(2)La6 octahedra, corners with five equivalent Se(3)La5 square pyramids, corners with four equivalent Se(1)La5 trigonal bipyramids,  an edgeedge with one Se(2)La6 octahedra, edges with four equivalent Se(1)La5 trigonal bipyramids, faces with two equivalent Se(2)La6 octahedra, and  a faceface with one Se(3)La5 square pyramid. The corner-sharing octahedral tilt angles range from 13-54°. is represented by the CIF card [CIF]
data_La2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   15.075
_cell_length_b   15.075
_cell_length_c   15.076
_cell_angle_alpha   144.828
_cell_angle_beta   144.830
_cell_angle_gamma   50.590
_symmetry_Int_Tables_number   1
_cell_volume   1131.047
_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
  La  La0  1  0.202  0.323  0.604  1.0
  La  La1  1  0.416  0.916  0.500  1.0
  La  La2  1  0.995  0.625  0.870  1.0
  La  La3  1  0.334  0.334  0.000  1.0
  La  La4  1  0.031  0.927  0.379  1.0
  La  La5  1  0.755  0.125  0.130  1.0
  La  La6  1  0.548  0.651  0.621  1.0
  La  La7  1  0.349  0.969  0.896  1.0
  La  La8  1  0.375  0.245  0.370  1.0
  La  La9  1  0.666  0.666  1.000  1.0
  La  La10  1  0.875  0.005  0.630  1.0
  La  La11  1  0.073  0.453  0.104  1.0
  La  La12  1  0.084  0.584  0.500  1.0
  La  La13  1  0.677  0.281  0.879  1.0
  La  La14  1  0.719  0.598  0.396  1.0
  La  La15  1  0.402  0.798  0.121  1.0
  Se  Se16  1  0.713  0.823  0.746  1.0
  Se  Se17  1  0.363  0.610  0.106  1.0
  Se  Se18  1  0.504  0.257  0.894  1.0
  Se  Se19  1  0.246  0.640  0.253  1.0
  Se  Se20  1  0.387  0.993  0.747  1.0
  Se  Se21  1  0.077  0.968  0.254  1.0
  Se  Se22  1  0.673  0.427  0.390  1.0
  Se  Se23  1  0.037  0.283  0.610  1.0
  Se  Se24  1  0.062  0.154  0.749  1.0
  Se  Se25  1  0.687  0.938  0.092  1.0
  Se  Se26  1  0.573  0.963  0.246  1.0
  Se  Se27  1  0.846  0.595  0.908  1.0
  Se  Se28  1  0.717  0.327  0.754  1.0
  Se  Se29  1  0.007  0.754  0.394  1.0
  Se  Se30  1  0.405  0.313  0.251  1.0
  Se  Se31  1  0.360  0.613  0.606  1.0
  Se  Se32  1  0.390  0.496  0.753  1.0
  Se  Se33  1  0.032  0.287  0.109  1.0
  Se  Se34  1  0.904  0.312  0.249  1.0
  Se  Se35  1  0.177  0.923  0.891  1.0
  Se  Se36  1  0.063  0.655  0.751  1.0
  Se  Se37  1  0.743  0.637  0.247  1.0
  Se  Se38  1  0.345  0.096  0.408  1.0
  Se  Se39  1  0.688  0.937  0.592  1.0
[/CIF]
.