data_BeSi2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.86
_cell_length_b   4.86
_cell_length_c   6.09
_cell_angle_alpha   114.56
_cell_angle_beta   114.56
_cell_angle_gamma   34.35
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BeSi2Se
_chemical_formula_sum   'Be1 Si2 Se1'
_cell_volume   72.9
_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
  Be  Be0  1  0.24  0.0  0.54  1.0
  Si  Si2  1  0.99  0.0  0.01  1.0
  Si  Si3  1  0.78  0.0  0.99  1.0
  Se  Se1  1  0.93  0.0  0.69  1.0

data_BeSi2Se
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.87
_cell_length_b   4.86
_cell_length_c   6.0
_cell_angle_alpha   67.23
_cell_angle_beta   76.19
_cell_angle_gamma   72.83
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BeSi2Se
_chemical_formula_sum   'Be1 Si2 Se1'
_cell_volume   72.9
_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
  Be  Be0  1  0.0  0.71  0.54  1.0
  Si  Si1  1  0.0  0.79  0.99  1.0
  Si  Si2  1  0.0  0.98  0.01  1.0
  Se  Se3  1  0.0  0.24  0.69  1.0

Be Si Si Se
Be Si Si Se 0 3 - o o 1 2 o o - 1 3 o o - 2 3 o o o 
BeSi2Se is Indium-like structured and crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one BeSi2Se cluster. Be(1) is bonded in a single-bond geometry to one Se(1) atom. The Be(1)-Se(1) bond length is 2.10 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a water-like geometry to one Si(2) and one Se(1) atom. The Si(1)-Si(2) bond length is 0.97 Å. The Si(1)-Se(1) bond length is 1.81 Å. In the second Si site, Si(2) is bonded in a single-bond geometry to one Si(1) atom. Se(1) is bonded in a distorted bent 120 degrees geometry to one Be(1) and one Si(1) atom.