data_NaPbSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.95
_cell_length_b   4.95
_cell_length_c   4.95
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaPbSe
_chemical_formula_sum   'Na1 Pb1 Se1'
_cell_volume   85.72
_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  Na0  1  0.0  0.0  0.0  1.0
  Pb  Pb1  1  0.75  0.75  0.75  1.0
  Se  Se2  1  0.25  0.25  0.25  1.0

data_NaPbSe
_symmetry_space_group_name_H-M   F-43m
_cell_length_a   7.0
_cell_length_b   7.0
_cell_length_c   7.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   216
_chemical_formula_structural   NaPbSe
_chemical_formula_sum   'Na4 Pb4 Se4'
_cell_volume   342.88
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'y, -x, -z'
  3  '-x, -y, z'
  4  '-y, x, -z'
  5  'x, -y, -z'
  6  'y, x, z'
  7  '-x, y, -z'
  8  '-y, -x, z'
  9  'z, x, y'
  10  '-z, y, -x'
  11  'z, -x, -y'
  12  '-z, -y, x'
  13  '-z, x, -y'
  14  'z, y, x'
  15  '-z, -x, y'
  16  'z, -y, -x'
  17  'y, z, x'
  18  '-x, -z, y'
  19  '-y, z, -x'
  20  'x, -z, -y'
  21  '-y, -z, x'
  22  'x, z, y'
  23  'y, -z, -x'
  24  '-x, z, -y'
  25  'x+1/2, y+1/2, z'
  26  'y+1/2, -x+1/2, -z'
  27  '-x+1/2, -y+1/2, z'
  28  '-y+1/2, x+1/2, -z'
  29  'x+1/2, -y+1/2, -z'
  30  'y+1/2, x+1/2, z'
  31  '-x+1/2, y+1/2, -z'
  32  '-y+1/2, -x+1/2, z'
  33  'z+1/2, x+1/2, y'
  34  '-z+1/2, y+1/2, -x'
  35  'z+1/2, -x+1/2, -y'
  36  '-z+1/2, -y+1/2, x'
  37  '-z+1/2, x+1/2, -y'
  38  'z+1/2, y+1/2, x'
  39  '-z+1/2, -x+1/2, y'
  40  'z+1/2, -y+1/2, -x'
  41  'y+1/2, z+1/2, x'
  42  '-x+1/2, -z+1/2, y'
  43  '-y+1/2, z+1/2, -x'
  44  'x+1/2, -z+1/2, -y'
  45  '-y+1/2, -z+1/2, x'
  46  'x+1/2, z+1/2, y'
  47  'y+1/2, -z+1/2, -x'
  48  '-x+1/2, z+1/2, -y'
  49  'x+1/2, y, z+1/2'
  50  'y+1/2, -x, -z+1/2'
  51  '-x+1/2, -y, z+1/2'
  52  '-y+1/2, x, -z+1/2'
  53  'x+1/2, -y, -z+1/2'
  54  'y+1/2, x, z+1/2'
  55  '-x+1/2, y, -z+1/2'
  56  '-y+1/2, -x, z+1/2'
  57  'z+1/2, x, y+1/2'
  58  '-z+1/2, y, -x+1/2'
  59  'z+1/2, -x, -y+1/2'
  60  '-z+1/2, -y, x+1/2'
  61  '-z+1/2, x, -y+1/2'
  62  'z+1/2, y, x+1/2'
  63  '-z+1/2, -x, y+1/2'
  64  'z+1/2, -y, -x+1/2'
  65  'y+1/2, z, x+1/2'
  66  '-x+1/2, -z, y+1/2'
  67  '-y+1/2, z, -x+1/2'
  68  'x+1/2, -z, -y+1/2'
  69  '-y+1/2, -z, x+1/2'
  70  'x+1/2, z, y+1/2'
  71  'y+1/2, -z, -x+1/2'
  72  '-x+1/2, z, -y+1/2'
  73  'x, y+1/2, z+1/2'
  74  'y, -x+1/2, -z+1/2'
  75  '-x, -y+1/2, z+1/2'
  76  '-y, x+1/2, -z+1/2'
  77  'x, -y+1/2, -z+1/2'
  78  'y, x+1/2, z+1/2'
  79  '-x, y+1/2, -z+1/2'
  80  '-y, -x+1/2, z+1/2'
  81  'z, x+1/2, y+1/2'
  82  '-z, y+1/2, -x+1/2'
  83  'z, -x+1/2, -y+1/2'
  84  '-z, -y+1/2, x+1/2'
  85  '-z, x+1/2, -y+1/2'
  86  'z, y+1/2, x+1/2'
  87  '-z, -x+1/2, y+1/2'
  88  'z, -y+1/2, -x+1/2'
  89  'y, z+1/2, x+1/2'
  90  '-x, -z+1/2, y+1/2'
  91  '-y, z+1/2, -x+1/2'
  92  'x, -z+1/2, -y+1/2'
  93  '-y, -z+1/2, x+1/2'
  94  'x, z+1/2, y+1/2'
  95  'y, -z+1/2, -x+1/2'
  96  '-x, z+1/2, -y+1/2'
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  4  0.0  0.0  0.0  1.0
  Pb  Pb1  4  0.25  0.25  0.25  1.0
  Se  Se2  4  0.25  0.25  0.75  1.0

Na Pb Se
Na Pb Se 0 2 o - o 0 2 - o o 0 2 o o - 0 2 o o o 0 1 - - - 0 1 - - o 0 1 - o - 0 1 o - - 1 2 o o + 1 2 o + o 1 2 o + + 1 2 + o o 1 2 + o + 1 2 + + o 
NaPbSe is half-Heusler structured and crystallizes in the trigonal R3m space group. Na(1) is bonded in a body-centered cubic geometry to four equivalent Pb(1) and four equivalent Se(1) atoms. All Na(1)-Pb(1) bond lengths are 3.03 Å. There is one shorter (3.02 Å) and three longer (3.03 Å) Na(1)-Se(1) bond lengths. Pb(1) is bonded to four equivalent Na(1) atoms to form PbNa4 tetrahedra that share corners with four equivalent Se(1)Na4 tetrahedra, corners with twelve equivalent Pb(1)Na4 tetrahedra, and edges with six equivalent Se(1)Na4 tetrahedra. Se(1) is bonded to four equivalent Na(1) atoms to form SeNa4 tetrahedra that share corners with four equivalent Pb(1)Na4 tetrahedra, corners with twelve equivalent Se(1)Na4 tetrahedra, and edges with six equivalent Pb(1)Na4 tetrahedra.