data_Nb2ZnSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.54
_cell_length_b   4.54
_cell_length_c   4.54
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb2ZnSe
_chemical_formula_sum   'Nb2 Zn1 Se1'
_cell_volume   65.98
_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
  Nb  Nb0  1  0.81  0.81  0.81  1.0
  Nb  Nb1  1  0.6  0.6  0.6  1.0
  Zn  Zn3  1  0.0  0.0  0.0  1.0
  Se  Se2  1  0.21  0.21  0.21  1.0

data_Nb2ZnSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.54
_cell_length_b   4.54
_cell_length_c   11.11
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Nb2ZnSe
_chemical_formula_sum   'Nb6 Zn3 Se3'
_cell_volume   197.93
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Nb  Nb0  3  0.0  0.0  0.19  1.0
  Nb  Nb1  3  0.0  0.0  0.4  1.0
  Zn  Zn2  3  0.0  0.0  0.0  1.0
  Se  Se3  3  0.0  0.0  0.79  1.0

Nb Nb Zn Se
Nb Nb Zn Se 0 1 o o o 0 1 o + o 0 1 + o o 0 1 o o + 0 2 + + + 0 3 + + o 0 3 + o + 0 3 o + + 1 3 o o + 1 3 o + o 1 3 + o o 1 2 o + + 1 2 + o + 1 2 + + o 2 3 o o o 2 3 o o - 2 3 - o o 2 3 o - o 
Nb2ZnSe crystallizes in the trigonal R3m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 5-coordinate geometry to one Nb(2), one Zn(1), and three equivalent Se(1) atoms. The Nb(1)-Nb(2) bond length is 2.30 Å. The Nb(1)-Zn(1) bond length is 2.10 Å. All Nb(1)-Se(1) bond lengths are 2.71 Å. In the second Nb site, Nb(2) is bonded in a 7-coordinate geometry to one Nb(1), three equivalent Zn(1), and three equivalent Se(1) atoms. All Nb(2)-Zn(1) bond lengths are 2.71 Å. All Nb(2)-Se(1) bond lengths are 2.71 Å. Zn(1) is bonded in a distorted linear geometry to one Nb(1), three equivalent Nb(2), and four equivalent Se(1) atoms. There is one shorter (2.30 Å) and three longer (2.97 Å) Zn(1)-Se(1) bond lengths. Se(1) is bonded in a 10-coordinate geometry to three equivalent Nb(1), three equivalent Nb(2), and four equivalent Zn(1) atoms.