data_Be2NiSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.14
_cell_length_b   3.14
_cell_length_c   4.76
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Be2NiSe
_chemical_formula_sum   'Be2 Ni1 Se1'
_cell_volume   46.96
_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  0.03  1.0
  Be  Be1  1  0.57  0.57  0.26  1.0
  Ni  Ni2  1  0.0  0.0  0.17  1.0
  Se  Se3  1  0.57  0.57  0.69  1.0

data_Be2NiSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.44
_cell_length_b   4.44
_cell_length_c   4.76
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Be2NiSe
_chemical_formula_sum   'Be4 Ni2 Se2'
_cell_volume   93.92
_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  0.03  1.0
  Be  Be1  2  0.07  0.5  0.26  1.0
  Ni  Ni2  2  0.0  0.0  0.17  1.0
  Se  Se3  2  0.07  0.5  0.69  1.0

Be Be Ni Se
Be2NiSe crystallizes in the monoclinic Cm space group. There are two inequivalent Be sites. In the first Be site, Be(1) is bonded in a single-bond geometry to one Ni(1) and three equivalent Se(1) atoms. The Be(1)-Ni(1) bond length is 0.66 Å. There is one shorter (2.50 Å) and two longer (2.76 Å) Be(1)-Se(1) bond lengths. In the second Be site, Be(2) is bonded in a 6-coordinate geometry to four equivalent Ni(1) and two equivalent Se(1) atoms. There are a spread of Be(2)-Ni(1) bond distances ranging from 1.95-2.57 Å. There is one shorter (2.06 Å) and one longer (2.70 Å) Be(2)-Se(1) bond length. Ni(1) is bonded in a single-bond geometry to one Be(1) and four equivalent Be(2) atoms. Se(1) is bonded in a 5-coordinate geometry to two equivalent Be(2) and three equivalent Be(1) atoms.