data_La2SiSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.61
_cell_length_b   3.61
_cell_length_c   7.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   La2SiSe
_chemical_formula_sum   'La2 Si1 Se1'
_cell_volume   102.68
_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
  La  La0  1  0.81  0.81  0.95  1.0
  La  La1  1  0.81  0.81  0.91  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0
  Se  Se2  1  0.0  0.0  0.93  1.0

data_La2SiSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.11
_cell_length_b   5.11
_cell_length_c   7.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   La2SiSe
_chemical_formula_sum   'La4 Si2 Se2'
_cell_volume   205.35
_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
  La  La0  2  0.31  0.5  0.91  1.0
  La  La1  2  0.31  0.5  0.95  1.0
  Si  Si2  2  0.0  0.0  0.0  1.0
  Se  Se3  2  0.0  0.0  0.93  1.0

La La Si Se
La La Si Se 0 1 o o o 2 3 o o - 
La2SiSe crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two La2SiSe clusters. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 2-coordinate geometry to one La(2) and one Se(1) atom. The La(1)-La(2) bond length is 0.35 Å. The La(1)-Se(1) bond length is 1.00 Å. In the second La site, La(2) is bonded in a distorted single-bond geometry to one La(1) atom. Si(1) is bonded in a single-bond geometry to one Se(1) atom. The Si(1)-Se(1) bond length is 0.54 Å. Se(1) is bonded in a distorted single-bond geometry to one La(1) and one Si(1) atom.