data_NaGeSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.88
_cell_length_b   3.88
_cell_length_c   6.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaGeSe2
_chemical_formula_sum   'Na1 Ge1 Se2'
_cell_volume   100.54
_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  0.95  1.0
  Ge  Ge0  1  0.94  0.94  0.01  1.0
  Se  Se2  1  0.94  0.94  0.36  1.0
  Se  Se3  1  0.0  0.0  0.34  1.0

data_NaGeSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.49
_cell_length_b   5.49
_cell_length_c   6.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaGeSe2
_chemical_formula_sum   'Na2 Ge2 Se4'
_cell_volume   201.07
_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  0.95  1.0
  Ge  Ge1  2  0.44  0.5  0.01  1.0
  Se  Se2  2  0.0  0.0  0.34  1.0
  Se  Se3  2  0.44  0.5  0.36  1.0

Na Ge Se Se
NaGeSe2 crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two NaGeSe2 clusters. Na(1) is bonded in a single-bond geometry to one Ge(1) atom. The Na(1)-Ge(1) bond length is 0.55 Å. Ge(1) is bonded in a single-bond geometry to one Na(1) and one Se(2) atom. The Ge(1)-Se(2) bond length is 2.18 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a single-bond geometry to one Se(2) atom. The Se(1)-Se(2) bond length is 0.34 Å. In the second Se site, Se(2) is bonded in a water-like geometry to one Ge(1) and one Se(1) atom.