data_MnSnSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.53
_cell_length_b   4.53
_cell_length_c   4.53
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MnSnSe
_chemical_formula_sum   'Mn1 Sn1 Se1'
_cell_volume   65.86
_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
  Mn  Mn0  1  0.0  0.0  0.0  1.0
  Sn  Sn2  1  0.81  0.81  0.81  1.0
  Se  Se1  1  0.6  0.6  0.6  1.0

data_MnSnSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.53
_cell_length_b   4.53
_cell_length_c   11.1
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MnSnSe
_chemical_formula_sum   'Mn3 Sn3 Se3'
_cell_volume   197.59
_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
  Mn  Mn0  3  0.0  0.0  0.0  1.0
  Sn  Sn1  3  0.0  0.0  0.19  1.0
  Se  Se2  3  0.0  0.0  0.4  1.0

Mn Sn Se
Mn Sn Se 0 1 - - - 0 2 - - o 0 2 - o - 0 2 o - - 1 2 o o o 1 2 o + o 1 2 + o o 1 2 o o + 
MnSnSe is half-Heusler structured and crystallizes in the trigonal R3m space group. Mn(1) is bonded in a 7-coordinate geometry to four equivalent Sn(1) and three equivalent Se(1) atoms. There is one shorter (2.13 Å) and three longer (3.05 Å) Mn(1)-Sn(1) bond lengths. All Mn(1)-Se(1) bond lengths are 2.71 Å. Sn(1) is bonded in a distorted linear geometry to four equivalent Mn(1) and four equivalent Se(1) atoms. There is one shorter (2.28 Å) and three longer (2.98 Å) Sn(1)-Se(1) bond lengths. Se(1) is bonded in a 7-coordinate geometry to three equivalent Mn(1) and four equivalent Sn(1) atoms.