data_NaBiSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.69
_cell_length_b   3.69
_cell_length_c   7.48
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaBiSe2
_chemical_formula_sum   'Na1 Bi1 Se2'
_cell_volume   101.95
_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
  Na  Na1  1  0.0  0.0  0.0  1.0
  Bi  Bi0  1  0.0  0.0  0.74  1.0
  Se  Se2  1  0.85  0.85  0.99  1.0
  Se  Se3  1  0.85  0.85  0.49  1.0

data_NaBiSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.22
_cell_length_b   5.22
_cell_length_c   7.48
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaBiSe2
_chemical_formula_sum   'Na2 Bi2 Se4'
_cell_volume   203.89
_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
  Na  Na0  2  0.0  0.0  0.0  1.0
  Bi  Bi1  2  0.0  0.0  0.74  1.0
  Se  Se2  2  0.35  0.5  0.49  1.0
  Se  Se3  2  0.35  0.5  0.99  1.0

Na Bi Se Se
NaBiSe2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two NaBiSe2 clusters. Na(1) is bonded in a distorted single-bond geometry to one Bi(1) and one Se(1) atom. The Na(1)-Bi(1) bond length is 1.95 Å. The Na(1)-Se(1) bond length is 0.81 Å. Bi(1) is bonded in a 3-coordinate geometry to one Na(1), one Se(1), and one Se(2) atom. The Bi(1)-Se(1) bond length is 2.05 Å. The Bi(1)-Se(2) bond length is 2.05 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a single-bond geometry to one Na(1) and one Bi(1) atom. In the second Se site, Se(2) is bonded in a single-bond geometry to one Bi(1) atom.