data_Na3Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.01
_cell_length_b   5.01
_cell_length_c   5.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na3Mg
_chemical_formula_sum   'Na3 Mg1'
_cell_volume   125.71
_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  0.5  0.5  1.0
  Na  Na2  1  0.5  0.0  0.5  1.0
  Na  Na3  1  0.5  0.5  0.0  1.0
  Mg  Mg0  1  0.0  0.0  0.0  1.0

data_Na3Mg
_symmetry_space_group_name_H-M   Pm-3m
_cell_length_a   5.01
_cell_length_b   5.01
_cell_length_c   5.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   221
_chemical_formula_structural   Na3Mg
_chemical_formula_sum   'Na3 Mg1'
_cell_volume   125.71
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-y, x, z'
  4  'y, -x, -z'
  5  '-x, -y, z'
  6  'x, y, -z'
  7  'y, -x, z'
  8  '-y, x, -z'
  9  'x, -y, -z'
  10  '-x, y, z'
  11  '-y, -x, -z'
  12  'y, x, z'
  13  '-x, y, -z'
  14  'x, -y, z'
  15  'y, x, -z'
  16  '-y, -x, z'
  17  'z, x, y'
  18  '-z, -x, -y'
  19  'z, -y, x'
  20  '-z, y, -x'
  21  'z, -x, -y'
  22  '-z, x, y'
  23  'z, y, -x'
  24  '-z, -y, x'
  25  '-z, x, -y'
  26  'z, -x, y'
  27  '-z, -y, -x'
  28  'z, y, x'
  29  '-z, -x, y'
  30  'z, x, -y'
  31  '-z, y, x'
  32  'z, -y, -x'
  33  'y, z, x'
  34  '-y, -z, -x'
  35  'x, z, -y'
  36  '-x, -z, y'
  37  '-y, z, -x'
  38  'y, -z, x'
  39  '-x, z, y'
  40  'x, -z, -y'
  41  '-y, -z, x'
  42  'y, z, -x'
  43  '-x, -z, -y'
  44  'x, z, y'
  45  'y, -z, -x'
  46  '-y, z, x'
  47  'x, -z, y'
  48  '-x, z, -y'
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  3  0.0  0.5  0.5  1.0
  Mg  Mg1  1  0.0  0.0  0.0  1.0

Na Na Na Mg
Na Na Na Mg 0 1 - o o 0 1 - + o 0 1 o o o 0 1 o + o 0 2 - o o 0 2 - o + 0 2 o o o 0 2 o o + 0 3 o o o 0 3 o o + 0 3 o + o 0 3 o + + 1 3 o o o 1 3 o o + 1 3 + o o 1 3 + o + 1 2 o - o 1 2 o - + 1 2 o o o 1 2 o o + 2 3 o o o 2 3 o + o 2 3 + o o 2 3 + + o 
Na3Mg is Uranium Silicide structured and crystallizes in the trigonal R3m space group. Na(1) is bonded to eight equivalent Na(1) and four equivalent Mg(1) atoms to form distorted NaNa8Mg4 cuboctahedra that share corners with twelve equivalent Na(1)Na8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Na12 cuboctahedra, edges with sixteen equivalent Na(1)Na8Mg4 cuboctahedra, faces with four equivalent Mg(1)Na12 cuboctahedra, and faces with fourteen equivalent Na(1)Na8Mg4 cuboctahedra. There are a spread of Na(1)-Na(1) bond distances ranging from 3.51-3.58 Å. There are a spread of Na(1)-Mg(1) bond distances ranging from 3.51-3.58 Å. Mg(1) is bonded to twelve equivalent Na(1) atoms to form MgNa12 cuboctahedra that share corners with twelve equivalent Mg(1)Na12 cuboctahedra, edges with twenty-four equivalent Na(1)Na8Mg4 cuboctahedra, faces with six equivalent Mg(1)Na12 cuboctahedra, and faces with twelve equivalent Na(1)Na8Mg4 cuboctahedra.