The crystal structure described by CeSe2 crystallizes in the tetragonal I4/m space group. There are two 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(3), one Se(4), and two equivalent Se(5) atoms to form corner-sharing CeSe4 tetrahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a bent 120 degrees geometry to two equivalent Ce(1) atoms. In the second Se site, Se(2) is bonded in a linear geometry to two equivalent Ce(1) atoms. In the third Se site, Se(3) is bonded in a bent 120 degrees geometry to one Ce(1) and one Ce(2) atom. In the fourth Se site, Se(4) is bonded in a bent 120 degrees geometry to one Ce(1) and one Ce(2) atom. In the fifth Se site, Se(5) is bonded in a bent 120 degrees geometry to two equivalent Ce(2) atoms. is represented by the CIF card [CIF]
data_CeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   17.547
_cell_length_b   18.340
_cell_length_c   18.340
_cell_angle_alpha   103.230
_cell_angle_beta   118.580
_cell_angle_gamma   61.420
_symmetry_Int_Tables_number   1
_cell_volume   4551.223
_cell_formula_units_Z   16
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  0.047  0.122  0.500  1.0
  Ce  Ce1  1  0.668  0.878  0.500  1.0
  Ce  Ce2  1  0.168  0.500  0.122  1.0
  Ce  Ce3  1  0.547  0.500  0.878  1.0
  Ce  Ce4  1  0.953  0.878  0.500  1.0
  Ce  Ce5  1  0.332  0.122  0.500  1.0
  Ce  Ce6  1  0.832  0.500  0.878  1.0
  Ce  Ce7  1  0.453  0.500  0.122  1.0
  Ce  Ce8  1  0.895  0.355  0.645  1.0
  Ce  Ce9  1  0.605  0.645  0.355  1.0
  Ce  Ce10  1  0.250  0.355  0.355  1.0
  Ce  Ce11  1  0.250  0.645  0.645  1.0
  Ce  Ce12  1  0.105  0.645  0.355  1.0
  Ce  Ce13  1  0.395  0.355  0.645  1.0
  Ce  Ce14  1  0.750  0.645  0.645  1.0
  Ce  Ce15  1  0.750  0.355  0.355  1.0
  Se  Se16  1  0.777  0.946  0.499  1.0
  Se  Se17  1  0.223  0.054  0.501  1.0
  Se  Se18  1  0.722  0.501  0.946  1.0
  Se  Se19  1  0.278  0.499  0.054  1.0
  Se  Se20  1  0.500  0.000  0.500  1.0
  Se  Se21  1  0.000  0.000  0.500  1.0
  Se  Se22  1  0.500  0.500  0.000  1.0
  Se  Se23  1  0.000  0.500  0.000  1.0
  Se  Se24  1  0.769  0.782  0.638  1.0
  Se  Se25  1  0.913  0.218  0.362  1.0
  Se  Se26  1  0.551  0.362  0.782  1.0
  Se  Se27  1  0.130  0.638  0.218  1.0
  Se  Se28  1  0.231  0.218  0.362  1.0
  Se  Se29  1  0.087  0.782  0.638  1.0
  Se  Se30  1  0.449  0.638  0.218  1.0
  Se  Se31  1  0.870  0.362  0.782  1.0
  Se  Se32  1  0.630  0.782  0.362  1.0
  Se  Se33  1  0.051  0.218  0.638  1.0
  Se  Se34  1  0.413  0.638  0.782  1.0
  Se  Se35  1  0.269  0.362  0.218  1.0
  Se  Se36  1  0.370  0.218  0.638  1.0
  Se  Se37  1  0.949  0.782  0.362  1.0
  Se  Se38  1  0.587  0.362  0.218  1.0
  Se  Se39  1  0.731  0.638  0.782  1.0
  Se  Se40  1  0.595  0.650  0.500  1.0
  Se  Se41  1  0.745  0.350  0.500  1.0
  Se  Se42  1  0.245  0.500  0.650  1.0
  Se  Se43  1  0.095  0.500  0.350  1.0
  Se  Se44  1  0.405  0.350  0.500  1.0
  Se  Se45  1  0.255  0.650  0.500  1.0
  Se  Se46  1  0.755  0.500  0.350  1.0
  Se  Se47  1  0.905  0.500  0.650  1.0
[/CIF]
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The crystal structure described by CeSe2 crystallizes in the tetragonal I4/m space group. There are two 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(3), one Se(4), and two equivalent Se(5) atoms to form corner-sharing CeSe4 tetrahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a bent 120 degrees geometry to two equivalent Ce(1) atoms. In the second Se site, Se(2) is bonded in a linear geometry to two equivalent Ce(1) atoms. In the third Se site, Se(3) is bonded in a bent 120 degrees geometry to one Ce(1) and one Ce(2) atom. In the fourth Se site, Se(4) is bonded in a bent 120 degrees geometry to one Ce(1) and one Ce(2) atom. In the fifth Se site, Se(5) is bonded in a bent 120 degrees geometry to two equivalent Ce(2) atoms. is represented by the CIF card [CIF]
data_CeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   17.547
_cell_length_b   18.340
_cell_length_c   18.340
_cell_angle_alpha   103.230
_cell_angle_beta   118.580
_cell_angle_gamma   61.420
_symmetry_Int_Tables_number   1
_cell_volume   4551.223
_cell_formula_units_Z   16
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  0.047  0.122  0.500  1.0
  Ce  Ce1  1  0.668  0.878  0.500  1.0
  Ce  Ce2  1  0.168  0.500  0.122  1.0
  Ce  Ce3  1  0.547  0.500  0.878  1.0
  Ce  Ce4  1  0.953  0.878  0.500  1.0
  Ce  Ce5  1  0.332  0.122  0.500  1.0
  Ce  Ce6  1  0.832  0.500  0.878  1.0
  Ce  Ce7  1  0.453  0.500  0.122  1.0
  Ce  Ce8  1  0.895  0.355  0.645  1.0
  Ce  Ce9  1  0.605  0.645  0.355  1.0
  Ce  Ce10  1  0.250  0.355  0.355  1.0
  Ce  Ce11  1  0.250  0.645  0.645  1.0
  Ce  Ce12  1  0.105  0.645  0.355  1.0
  Ce  Ce13  1  0.395  0.355  0.645  1.0
  Ce  Ce14  1  0.750  0.645  0.645  1.0
  Ce  Ce15  1  0.750  0.355  0.355  1.0
  Se  Se16  1  0.777  0.946  0.499  1.0
  Se  Se17  1  0.223  0.054  0.501  1.0
  Se  Se18  1  0.722  0.501  0.946  1.0
  Se  Se19  1  0.278  0.499  0.054  1.0
  Se  Se20  1  0.500  0.000  0.500  1.0
  Se  Se21  1  0.000  0.000  0.500  1.0
  Se  Se22  1  0.500  0.500  0.000  1.0
  Se  Se23  1  0.000  0.500  0.000  1.0
  Se  Se24  1  0.769  0.782  0.638  1.0
  Se  Se25  1  0.913  0.218  0.362  1.0
  Se  Se26  1  0.551  0.362  0.782  1.0
  Se  Se27  1  0.130  0.638  0.218  1.0
  Se  Se28  1  0.231  0.218  0.362  1.0
  Se  Se29  1  0.087  0.782  0.638  1.0
  Se  Se30  1  0.449  0.638  0.218  1.0
  Se  Se31  1  0.870  0.362  0.782  1.0
  Se  Se32  1  0.630  0.782  0.362  1.0
  Se  Se33  1  0.051  0.218  0.638  1.0
  Se  Se34  1  0.413  0.638  0.782  1.0
  Se  Se35  1  0.269  0.362  0.218  1.0
  Se  Se36  1  0.370  0.218  0.638  1.0
  Se  Se37  1  0.949  0.782  0.362  1.0
  Se  Se38  1  0.587  0.362  0.218  1.0
  Se  Se39  1  0.731  0.638  0.782  1.0
  Se  Se40  1  0.595  0.650  0.500  1.0
  Se  Se41  1  0.745  0.350  0.500  1.0
  Se  Se42  1  0.245  0.500  0.650  1.0
  Se  Se43  1  0.095  0.500  0.350  1.0
  Se  Se44  1  0.405  0.350  0.500  1.0
  Se  Se45  1  0.255  0.650  0.500  1.0
  Se  Se46  1  0.755  0.500  0.350  1.0
  Se  Se47  1  0.905  0.500  0.650  1.0
[/CIF]
.