data_NiSnSe
_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   NiSnSe
_chemical_formula_sum   'Ni1 Sn1 Se1'
_cell_volume   66.01
_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
  Ni  Ni0  1  0.0  0.0  0.0  1.0
  Sn  Sn2  1  0.21  0.21  0.21  1.0
  Se  Se1  1  0.6  0.6  0.6  1.0

data_NiSnSe
_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   NiSnSe
_chemical_formula_sum   'Ni3 Sn3 Se3'
_cell_volume   198.02
_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
  Ni  Ni0  3  0.0  0.0  0.0  1.0
  Sn  Sn1  3  0.0  0.0  0.79  1.0
  Se  Se2  3  0.0  0.0  0.4  1.0

Ni Sn Se
NiSnSe crystallizes in the trigonal R3m space group. Ni(1) is bonded to one Sn(1) and three equivalent Se(1) atoms to form distorted NiSnSe3 tetrahedra that share corners with three equivalent Sn(1)NiSe3 tetrahedra, corners with six equivalent Ni(1)SnSe3 tetrahedra, and edges with three equivalent Sn(1)NiSe3 tetrahedra. The Ni(1)-Sn(1) bond length is 2.31 Å. All Ni(1)-Se(1) bond lengths are 2.71 Å. Sn(1) is bonded to one Ni(1) and three equivalent Se(1) atoms to form distorted SnNiSe3 tetrahedra that share corners with three equivalent Ni(1)SnSe3 tetrahedra, corners with six equivalent Sn(1)NiSe3 tetrahedra, and edges with three equivalent Ni(1)SnSe3 tetrahedra. All Sn(1)-Se(1) bond lengths are 2.71 Å. Se(1) is bonded in a distorted hexagonal planar geometry to three equivalent Ni(1) and three equivalent Sn(1) atoms.