The structure described by CeSe2 is Low Tridymite-like structured and crystallizes in the orthorhombic Fmmm space group. There are four inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form corner-sharing CeSe4 tetrahedra. In the second Ce site, Ce(2) is bonded to one Se(5), one Se(6), and two equivalent Se(3) atoms to form corner-sharing CeSe4 tetrahedra. In the third Ce site, Ce(3) is bonded to one Se(5), one Se(7), and two equivalent Se(2) atoms to form corner-sharing CeSe4 tetrahedra. In the fourth Ce site, Ce(4) is bonded to four equivalent Se(1) atoms to form corner-sharing CeSe4 tetrahedra. There are seven inequivalent Se sites. In the first Se site, Se(4) is bonded in a bent 150 degrees geometry to two equivalent Ce(1) atoms. In the second Se site, Se(5) is bonded in a bent 150 degrees geometry to one Ce(2) and one Ce(3) atom. In the third Se site, Se(1) is bonded in a bent 150 degrees geometry to one Ce(1) and one Ce(4) atom. In the fourth Se site, Se(6) is bonded in a linear geometry to two equivalent Ce(2) atoms. In the fifth Se site, Se(7) is bonded in a bent 150 degrees geometry to two equivalent Ce(3) atoms. In the sixth Se site, Se(2) is bonded in a bent 150 degrees geometry to one Ce(1) and one Ce(3) atom. In the seventh Se site, Se(3) is bonded in a bent 150 degrees 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   18.707
_cell_length_b   18.707
_cell_length_c   18.958
_cell_angle_alpha   111.237
_cell_angle_beta   111.237
_cell_angle_gamma   105.416
_symmetry_Int_Tables_number   1
_cell_volume   5126.497
_cell_formula_units_Z   18
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  0.323  0.074  0.622  1.0
  Ce  Ce1  1  0.452  0.701  0.378  1.0
  Ce  Ce2  1  0.299  0.548  0.622  1.0
  Ce  Ce3  1  0.926  0.677  0.378  1.0
  Ce  Ce4  1  0.677  0.926  0.378  1.0
  Ce  Ce5  1  0.548  0.299  0.622  1.0
  Ce  Ce6  1  0.701  0.452  0.378  1.0
  Ce  Ce7  1  0.074  0.323  0.622  1.0
  Ce  Ce8  1  0.216  0.216  0.821  1.0
  Ce  Ce9  1  0.394  0.394  0.179  1.0
  Ce  Ce10  1  0.606  0.606  0.821  1.0
  Ce  Ce11  1  0.784  0.784  0.179  1.0
  Ce  Ce12  1  0.074  0.074  0.371  1.0
  Ce  Ce13  1  0.703  0.703  0.629  1.0
  Ce  Ce14  1  0.297  0.297  0.371  1.0
  Ce  Ce15  1  0.926  0.926  0.629  1.0
  Ce  Ce16  1  0.250  0.750  0.500  1.0
  Ce  Ce17  1  0.750  0.250  0.500  1.0
  Se  Se18  1  0.320  0.923  0.609  1.0
  Se  Se19  1  0.314  0.711  0.391  1.0
  Se  Se20  1  0.289  0.686  0.609  1.0
  Se  Se21  1  0.077  0.680  0.391  1.0
  Se  Se22  1  0.680  0.077  0.391  1.0
  Se  Se23  1  0.686  0.289  0.609  1.0
  Se  Se24  1  0.711  0.314  0.391  1.0
  Se  Se25  1  0.923  0.320  0.609  1.0
  Se  Se26  1  0.184  0.035  0.472  1.0
  Se  Se27  1  0.563  0.712  0.528  1.0
  Se  Se28  1  0.288  0.437  0.472  1.0
  Se  Se29  1  0.965  0.816  0.528  1.0
  Se  Se30  1  0.816  0.965  0.528  1.0
  Se  Se31  1  0.437  0.288  0.472  1.0
  Se  Se32  1  0.712  0.563  0.528  1.0
  Se  Se33  1  0.035  0.184  0.472  1.0
  Se  Se34  1  0.322  0.170  0.769  1.0
  Se  Se35  1  0.401  0.553  0.231  1.0
  Se  Se36  1  0.447  0.599  0.769  1.0
  Se  Se37  1  0.830  0.678  0.231  1.0
  Se  Se38  1  0.678  0.830  0.231  1.0
  Se  Se39  1  0.599  0.447  0.769  1.0
  Se  Se40  1  0.553  0.401  0.231  1.0
  Se  Se41  1  0.170  0.322  0.769  1.0
  Se  Se42  1  0.475  0.169  0.644  1.0
  Se  Se43  1  0.525  0.831  0.356  1.0
  Se  Se44  1  0.169  0.475  0.644  1.0
  Se  Se45  1  0.831  0.525  0.356  1.0
  Se  Se46  1  0.927  0.927  0.236  1.0
  Se  Se47  1  0.691  0.691  0.764  1.0
  Se  Se48  1  0.309  0.309  0.236  1.0
  Se  Se49  1  0.073  0.073  0.764  1.0
  Se  Se50  1  0.311  0.311  0.000  1.0
  Se  Se51  1  0.689  0.689  0.000  1.0
  Se  Se52  1  0.154  0.154  0.307  1.0
  Se  Se53  1  0.846  0.846  0.693  1.0
[/CIF]
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The structure described by CeSe2 is Low Tridymite-like structured and crystallizes in the orthorhombic Fmmm space group. There are four inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form corner-sharing CeSe4 tetrahedra. In the second Ce site, Ce(2) is bonded to one Se(5), one Se(6), and two equivalent Se(3) atoms to form corner-sharing CeSe4 tetrahedra. In the third Ce site, Ce(3) is bonded to one Se(5), one Se(7), and two equivalent Se(2) atoms to form corner-sharing CeSe4 tetrahedra. In the fourth Ce site, Ce(4) is bonded to four equivalent Se(1) atoms to form corner-sharing CeSe4 tetrahedra. There are seven inequivalent Se sites. In the first Se site, Se(4) is bonded in a bent 150 degrees geometry to two equivalent Ce(1) atoms. In the second Se site, Se(5) is bonded in a bent 150 degrees geometry to one Ce(2) and one Ce(3) atom. In the third Se site, Se(1) is bonded in a bent 150 degrees geometry to one Ce(1) and one Ce(4) atom. In the fourth Se site, Se(6) is bonded in a linear geometry to two equivalent Ce(2) atoms. In the fifth Se site, Se(7) is bonded in a bent 150 degrees geometry to two equivalent Ce(3) atoms. In the sixth Se site, Se(2) is bonded in a bent 150 degrees geometry to one Ce(1) and one Ce(3) atom. In the seventh Se site, Se(3) is bonded in a bent 150 degrees 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   18.707
_cell_length_b   18.707
_cell_length_c   18.958
_cell_angle_alpha   111.237
_cell_angle_beta   111.237
_cell_angle_gamma   105.416
_symmetry_Int_Tables_number   1
_cell_volume   5126.497
_cell_formula_units_Z   18
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  0.323  0.074  0.622  1.0
  Ce  Ce1  1  0.452  0.701  0.378  1.0
  Ce  Ce2  1  0.299  0.548  0.622  1.0
  Ce  Ce3  1  0.926  0.677  0.378  1.0
  Ce  Ce4  1  0.677  0.926  0.378  1.0
  Ce  Ce5  1  0.548  0.299  0.622  1.0
  Ce  Ce6  1  0.701  0.452  0.378  1.0
  Ce  Ce7  1  0.074  0.323  0.622  1.0
  Ce  Ce8  1  0.216  0.216  0.821  1.0
  Ce  Ce9  1  0.394  0.394  0.179  1.0
  Ce  Ce10  1  0.606  0.606  0.821  1.0
  Ce  Ce11  1  0.784  0.784  0.179  1.0
  Ce  Ce12  1  0.074  0.074  0.371  1.0
  Ce  Ce13  1  0.703  0.703  0.629  1.0
  Ce  Ce14  1  0.297  0.297  0.371  1.0
  Ce  Ce15  1  0.926  0.926  0.629  1.0
  Ce  Ce16  1  0.250  0.750  0.500  1.0
  Ce  Ce17  1  0.750  0.250  0.500  1.0
  Se  Se18  1  0.320  0.923  0.609  1.0
  Se  Se19  1  0.314  0.711  0.391  1.0
  Se  Se20  1  0.289  0.686  0.609  1.0
  Se  Se21  1  0.077  0.680  0.391  1.0
  Se  Se22  1  0.680  0.077  0.391  1.0
  Se  Se23  1  0.686  0.289  0.609  1.0
  Se  Se24  1  0.711  0.314  0.391  1.0
  Se  Se25  1  0.923  0.320  0.609  1.0
  Se  Se26  1  0.184  0.035  0.472  1.0
  Se  Se27  1  0.563  0.712  0.528  1.0
  Se  Se28  1  0.288  0.437  0.472  1.0
  Se  Se29  1  0.965  0.816  0.528  1.0
  Se  Se30  1  0.816  0.965  0.528  1.0
  Se  Se31  1  0.437  0.288  0.472  1.0
  Se  Se32  1  0.712  0.563  0.528  1.0
  Se  Se33  1  0.035  0.184  0.472  1.0
  Se  Se34  1  0.322  0.170  0.769  1.0
  Se  Se35  1  0.401  0.553  0.231  1.0
  Se  Se36  1  0.447  0.599  0.769  1.0
  Se  Se37  1  0.830  0.678  0.231  1.0
  Se  Se38  1  0.678  0.830  0.231  1.0
  Se  Se39  1  0.599  0.447  0.769  1.0
  Se  Se40  1  0.553  0.401  0.231  1.0
  Se  Se41  1  0.170  0.322  0.769  1.0
  Se  Se42  1  0.475  0.169  0.644  1.0
  Se  Se43  1  0.525  0.831  0.356  1.0
  Se  Se44  1  0.169  0.475  0.644  1.0
  Se  Se45  1  0.831  0.525  0.356  1.0
  Se  Se46  1  0.927  0.927  0.236  1.0
  Se  Se47  1  0.691  0.691  0.764  1.0
  Se  Se48  1  0.309  0.309  0.236  1.0
  Se  Se49  1  0.073  0.073  0.764  1.0
  Se  Se50  1  0.311  0.311  0.000  1.0
  Se  Se51  1  0.689  0.689  0.000  1.0
  Se  Se52  1  0.154  0.154  0.307  1.0
  Se  Se53  1  0.846  0.846  0.693  1.0
[/CIF]
.