The crystal structure described by CeSe2 is Low Tridymite-like structured and crystallizes in the monoclinic C2/m space group. There are seven inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form corner-sharing CeSe4 tetrahedra. In the second Ce site, Ce(2) is bonded to one Se(1), one Se(2), and two equivalent Se(5) atoms to form corner-sharing CeSe4 tetrahedra. In the third Ce site, Ce(3) is bonded to one Se(4), one Se(6), and two equivalent Se(3) atoms to form corner-sharing CeSe4 tetrahedra. In the fourth Ce site, Ce(4) is bonded to one Se(10), one Se(9), and two equivalent Se(5) atoms to form corner-sharing CeSe4 tetrahedra. In the fifth Ce site, Ce(5) is bonded to one Se(10), one Se(4), and two equivalent Se(8) atoms to form corner-sharing CeSe4 tetrahedra. In the sixth Ce site, Ce(6) is bonded to one Se(11), one Se(9), and two equivalent Se(8) atoms to form corner-sharing CeSe4 tetrahedra. In the seventh Ce site, Ce(7) is bonded to one Se(11), one Se(6), and two equivalent Se(7) atoms to form corner-sharing CeSe4 tetrahedra. There are eleven inequivalent Se sites. In the first Se site, Se(3) is bonded in a bent 150 degrees geometry to one Ce(1) and one Ce(3) atom. In the second Se site, Se(4) is bonded in a bent 150 degrees geometry to one Ce(3) and one Ce(5) atom. In the third Se site, Se(5) is bonded in a bent 150 degrees geometry to one Ce(2) and one Ce(4) atom. In the fourth Se site, Se(6) is bonded in a bent 120 degrees geometry to one Ce(3) and one Ce(7) atom. In the fifth Se site, Se(7) is bonded in a linear geometry to two equivalent Ce(7) atoms. In the sixth Se site, Se(8) is bonded in a bent 150 degrees geometry to one Ce(5) and one Ce(6) atom. In the seventh Se site, Se(9) is bonded in a bent 150 degrees geometry to one Ce(4) and one Ce(6) atom. In the eighth Se site, Se(10) is bonded in a bent 150 degrees geometry to one Ce(4) and one Ce(5) atom. In the ninth Se site, Se(11) is bonded in a linear geometry to one Ce(6) and one Ce(7) atom. In the tenth Se site, Se(1) is bonded in a bent 120 degrees geometry to one Ce(1) and one Ce(2) atom. In the eleventh Se site, Se(2) is bonded in a linear geometry to one Ce(1) and one Ce(2) atom. is represented by the CIF file [CIF]
data_CeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.609
_cell_length_b   20.437
_cell_length_c   21.621
_cell_angle_alpha   108.053
_cell_angle_beta   101.484
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   3536.718
_cell_formula_units_Z   14
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
  Ce  Ce0  1  0.071  0.159  0.143  1.0
  Ce  Ce1  1  0.929  0.841  0.857  1.0
  Ce  Ce2  1  0.062  0.913  0.125  1.0
  Ce  Ce3  1  0.938  0.087  0.875  1.0
  Ce  Ce4  1  0.369  0.709  0.739  1.0
  Ce  Ce5  1  0.631  0.291  0.261  1.0
  Ce  Ce6  1  0.381  0.120  0.761  1.0
  Ce  Ce7  1  0.619  0.880  0.239  1.0
  Ce  Ce8  1  0.293  0.866  0.587  1.0
  Ce  Ce9  1  0.707  0.134  0.413  1.0
  Ce  Ce10  1  0.279  0.210  0.558  1.0
  Ce  Ce11  1  0.721  0.790  0.442  1.0
  Ce  Ce12  1  0.284  0.478  0.568  1.0
  Ce  Ce13  1  0.716  0.522  0.432  1.0
  Se  Se14  1  0.096  0.051  0.193  1.0
  Se  Se15  1  0.904  0.949  0.807  1.0
  Se  Se16  1  0.004  0.108  0.009  1.0
  Se  Se17  1  0.996  0.892  0.991  1.0
  Se  Se18  1  0.842  0.244  0.182  1.0
  Se  Se19  1  0.340  0.244  0.182  1.0
  Se  Se20  1  0.158  0.756  0.818  1.0
  Se  Se21  1  0.660  0.756  0.818  1.0
  Se  Se22  1  0.316  0.755  0.631  1.0
  Se  Se23  1  0.684  0.245  0.369  1.0
  Se  Se24  1  0.672  0.152  0.844  1.0
  Se  Se25  1  0.172  0.152  0.844  1.0
  Se  Se26  1  0.328  0.848  0.156  1.0
  Se  Se27  1  0.828  0.848  0.156  1.0
  Se  Se28  1  0.347  0.569  0.694  1.0
  Se  Se29  1  0.653  0.431  0.306  1.0
  Se  Se30  1  0.000  0.500  0.500  1.0
  Se  Se31  1  0.500  0.500  0.500  1.0
  Se  Se32  1  0.997  0.139  0.493  1.0
  Se  Se33  1  0.496  0.139  0.493  1.0
  Se  Se34  1  0.003  0.861  0.507  1.0
  Se  Se35  1  0.504  0.861  0.507  1.0
  Se  Se36  1  0.342  0.205  0.685  1.0
  Se  Se37  1  0.658  0.795  0.315  1.0
  Se  Se38  1  0.345  0.985  0.690  1.0
  Se  Se39  1  0.655  0.015  0.310  1.0
  Se  Se40  1  0.283  0.345  0.566  1.0
  Se  Se41  1  0.717  0.655  0.434  1.0
[/CIF]
.
The crystal structure described by CeSe2 is Low Tridymite-like structured and crystallizes in the monoclinic C2/m space group. There are seven inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form corner-sharing CeSe4 tetrahedra. In the second Ce site, Ce(2) is bonded to one Se(1), one Se(2), and two equivalent Se(5) atoms to form corner-sharing CeSe4 tetrahedra. In the third Ce site, Ce(3) is bonded to one Se(4), one Se(6), and two equivalent Se(3) atoms to form corner-sharing CeSe4 tetrahedra. In the fourth Ce site, Ce(4) is bonded to one Se(10), one Se(9), and two equivalent Se(5) atoms to form corner-sharing CeSe4 tetrahedra. In the fifth Ce site, Ce(5) is bonded to one Se(10), one Se(4), and two equivalent Se(8) atoms to form corner-sharing CeSe4 tetrahedra. In the sixth Ce site, Ce(6) is bonded to one Se(11), one Se(9), and two equivalent Se(8) atoms to form corner-sharing CeSe4 tetrahedra. In the seventh Ce site, Ce(7) is bonded to one Se(11), one Se(6), and two equivalent Se(7) atoms to form corner-sharing CeSe4 tetrahedra. There are eleven inequivalent Se sites. In the first Se site, Se(3) is bonded in a bent 150 degrees geometry to one Ce(1) and one Ce(3) atom. In the second Se site, Se(4) is bonded in a bent 150 degrees geometry to one Ce(3) and one Ce(5) atom. In the third Se site, Se(5) is bonded in a bent 150 degrees geometry to one Ce(2) and one Ce(4) atom. In the fourth Se site, Se(6) is bonded in a bent 120 degrees geometry to one Ce(3) and one Ce(7) atom. In the fifth Se site, Se(7) is bonded in a linear geometry to two equivalent Ce(7) atoms. In the sixth Se site, Se(8) is bonded in a bent 150 degrees geometry to one Ce(5) and one Ce(6) atom. In the seventh Se site, Se(9) is bonded in a bent 150 degrees geometry to one Ce(4) and one Ce(6) atom. In the eighth Se site, Se(10) is bonded in a bent 150 degrees geometry to one Ce(4) and one Ce(5) atom. In the ninth Se site, Se(11) is bonded in a linear geometry to one Ce(6) and one Ce(7) atom. In the tenth Se site, Se(1) is bonded in a bent 120 degrees geometry to one Ce(1) and one Ce(2) atom. In the eleventh Se site, Se(2) is bonded in a linear geometry to one Ce(1) and one Ce(2) atom. is represented by the CIF file [CIF]
data_CeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.609
_cell_length_b   20.437
_cell_length_c   21.621
_cell_angle_alpha   108.053
_cell_angle_beta   101.484
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   3536.718
_cell_formula_units_Z   14
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
  Ce  Ce0  1  0.071  0.159  0.143  1.0
  Ce  Ce1  1  0.929  0.841  0.857  1.0
  Ce  Ce2  1  0.062  0.913  0.125  1.0
  Ce  Ce3  1  0.938  0.087  0.875  1.0
  Ce  Ce4  1  0.369  0.709  0.739  1.0
  Ce  Ce5  1  0.631  0.291  0.261  1.0
  Ce  Ce6  1  0.381  0.120  0.761  1.0
  Ce  Ce7  1  0.619  0.880  0.239  1.0
  Ce  Ce8  1  0.293  0.866  0.587  1.0
  Ce  Ce9  1  0.707  0.134  0.413  1.0
  Ce  Ce10  1  0.279  0.210  0.558  1.0
  Ce  Ce11  1  0.721  0.790  0.442  1.0
  Ce  Ce12  1  0.284  0.478  0.568  1.0
  Ce  Ce13  1  0.716  0.522  0.432  1.0
  Se  Se14  1  0.096  0.051  0.193  1.0
  Se  Se15  1  0.904  0.949  0.807  1.0
  Se  Se16  1  0.004  0.108  0.009  1.0
  Se  Se17  1  0.996  0.892  0.991  1.0
  Se  Se18  1  0.842  0.244  0.182  1.0
  Se  Se19  1  0.340  0.244  0.182  1.0
  Se  Se20  1  0.158  0.756  0.818  1.0
  Se  Se21  1  0.660  0.756  0.818  1.0
  Se  Se22  1  0.316  0.755  0.631  1.0
  Se  Se23  1  0.684  0.245  0.369  1.0
  Se  Se24  1  0.672  0.152  0.844  1.0
  Se  Se25  1  0.172  0.152  0.844  1.0
  Se  Se26  1  0.328  0.848  0.156  1.0
  Se  Se27  1  0.828  0.848  0.156  1.0
  Se  Se28  1  0.347  0.569  0.694  1.0
  Se  Se29  1  0.653  0.431  0.306  1.0
  Se  Se30  1  0.000  0.500  0.500  1.0
  Se  Se31  1  0.500  0.500  0.500  1.0
  Se  Se32  1  0.997  0.139  0.493  1.0
  Se  Se33  1  0.496  0.139  0.493  1.0
  Se  Se34  1  0.003  0.861  0.507  1.0
  Se  Se35  1  0.504  0.861  0.507  1.0
  Se  Se36  1  0.342  0.205  0.685  1.0
  Se  Se37  1  0.658  0.795  0.315  1.0
  Se  Se38  1  0.345  0.985  0.690  1.0
  Se  Se39  1  0.655  0.015  0.310  1.0
  Se  Se40  1  0.283  0.345  0.566  1.0
  Se  Se41  1  0.717  0.655  0.434  1.0
[/CIF]
.