data_BeTeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.67
_cell_length_b   3.67
_cell_length_c   7.11
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   BeTeSe2
_chemical_formula_sum   'Be1 Te1 Se2'
_cell_volume   95.92
_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  0.0  0.0  1.0
  Te  Te3  1  0.84  0.84  0.0  1.0
  Se  Se1  1  0.0  0.84  0.56  1.0
  Se  Se2  1  0.84  0.0  0.56  1.0

data_BeTeSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.19
_cell_length_b   5.19
_cell_length_c   7.11
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   BeTeSe2
_chemical_formula_sum   'Be2 Te2 Se4'
_cell_volume   191.84
_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
  Be  Be0  2  0.0  0.0  0.0  1.0
  Te  Te1  2  0.34  0.5  -0.0  1.0
  Se  Se2  4  0.42  0.42  0.56  1.0

Be Te Se Se
Be Te Se Se 0 1 - - o 2 3 - + o 
BeTe(Se)2 is alpha carbon monoxide-derived structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two beryllium telluride molecules and two diselenium molecules.