data_YFeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   3.51
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   YFeSe2
_chemical_formula_sum   'Y1 Fe1 Se2'
_cell_volume   79.58
_cell_formula_units_Z   1
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
  Y  Y3  1  0.38  0.38  0.0  1.0
  Fe  Fe0  1  0.0  0.0  0.0  1.0
  Se  Se1  1  0.0  0.38  0.76  1.0
  Se  Se2  1  0.38  0.0  0.76  1.0

data_YFeSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.73
_cell_length_b   6.73
_cell_length_c   3.51
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   YFeSe2
_chemical_formula_sum   'Y2 Fe2 Se4'
_cell_volume   159.15
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Y  Y0  2  0.38  0.0  0.0  1.0
  Fe  Fe1  2  0.0  0.0  0.0  1.0
  Se  Se2  4  0.19  0.19  0.76  1.0

Y Fe Se Se
YFeSe2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two YFeSe2 clusters. Y(1) is bonded in a 2-coordinate geometry to two equivalent Se(1) atoms. Both Y(1)-Se(1) bond lengths are 2.00 Å. Fe(1) is bonded in a 2-coordinate geometry to two equivalent Se(1) atoms. Both Fe(1)-Se(1) bond lengths are 2.00 Å. Se(1) is bonded in a 2-coordinate geometry to one Y(1) and one Fe(1) atom.